Adding write support to File_Format.Excel (#3551)

Support for writing tables to Excel.

# Important Notes
Has custom support for Error mode as will allow appending a new table in this mode to the file.

CHANGELOG.md

@@ -144,6 +144,7 @@
 - [Removed obsolete `from_xls` and `from_xlsx` functions. Added support for
   reading column names from first row in `File_Format.Excel`][3523]
 - [Added `File_Format.Delimited` support to `Table.write` for new files.][3528]
+- [Added `File_Format.Excel` support to `Table.write` for new files.][3551]
 
 [debug-shortcuts]:
   https://github.com/enso-org/enso/blob/develop/app/gui/docs/product/shortcuts.md#debug
@@ -227,6 +228,7 @@
 [3519]: https://github.com/enso-org/enso/pull/3519
 [3523]: https://github.com/enso-org/enso/pull/3523
 [3528]: https://github.com/enso-org/enso/pull/3528
+[3551]: https://github.com/enso-org/enso/pull/3551
 
 #### Enso Compiler
 

distribution/lib/Standard/Base/0.0.0-dev/src/System/File.enso

@@ -524,9 +524,30 @@ type File
        Arguments:
        - destination: the destination to move the file to.
        - replace_existing: specifies if the operation should proceed if the
-         destination file already exists. Defaults to `True`.
+         destination file already exists. Defaults to `False`.
+    copy_to : File -> Boolean -> Nothing ! File_Error
+    copy_to destination replace_existing=False =
+        here.handle_java_exceptions self <| case replace_existing of
+            True ->
+              copy_options = Array.new_1 StandardCopyOption.REPLACE_EXISTING
+              self.copy_builtin destination copy_options
+            False -> self.copy_builtin destination Array.empty
+
+    ## PRIVATE
+
+       Builtin method that copies this file to a new destination.
+       Recommended to use `File.copy_to` instead which handles potential exceptions.
+    copy_builtin : File -> Array Any -> Nothing
+    copy_builtin destination copy_options = @Builtin_Method "File.copy_builtin"
+
+    ## Moves the file to the specified destination.
+
+       Arguments:
+       - destination: the destination to move the file to.
+       - replace_existing: specifies if the operation should proceed if the
+         destination file already exists. Defaults to `False`.
     move_to : File -> Boolean -> Nothing ! File_Error
-    move_to destination replace_existing=True =
+    move_to destination replace_existing=False =
         here.handle_java_exceptions self <| case replace_existing of
             True ->
               copy_options = Array.new_1 StandardCopyOption.REPLACE_EXISTING

distribution/lib/Standard/Base/0.0.0-dev/src/System/File/Existing_File_Behavior.enso

@@ -96,7 +96,7 @@ write_file_backing_up_old_one file action = Panic.recover [Io_Error, File_Not_Fo
                to back-up anymore, but this is not a failure, so it can be
                safely ignored.
             Panic.catch File_Not_Found handler=(_->Nothing) <|
-                Panic.rethrow <| file.move_to bak_file
+                Panic.rethrow <| file.move_to bak_file replace_existing=True
             Panic.rethrow <| new_file.move_to file
     go 0
 

distribution/lib/Standard/Searcher/0.0.0-dev/src/Data_Science.enso

@@ -21,7 +21,7 @@
 
          example_to_xlsx =
              path = Enso_Project.data / example_xlsx_output.xlsx
-             Examples.inventory_table.write_xlsx path
+             Examples.inventory_table.write path
 
    > Example
      Join multiple tables together. It joins tables on their indices, so we need

distribution/lib/Standard/Searcher/0.0.0-dev/src/Data_Science/Input_And_Output.enso

@@ -30,7 +30,7 @@
 
          example_to_xlsx =
              path = Enso_Project.data / example_xlsx_output.xlsx
-             Examples.inventory_table.write_xlsx path
+             Examples.inventory_table.write path
 
    > Example
      Write a table to a CSV file.

distribution/lib/Standard/Table/0.0.0-dev/package.yaml

@@ -35,4 +35,4 @@ component-groups:
           - Standard.Table.Data.Column.Column.to_table
     - Standard.Base.Output:
         exports:
-          - Standard.Table.Data.Table.Table.write_xlsx
+          - Standard.Table.Data.Table.Table.write

distribution/lib/Standard/Table/0.0.0-dev/src/Data/Table.enso

@@ -4,7 +4,6 @@ import Standard.Base.System.Platform
 import Standard.Table.Data.Column
 import Standard.Visualization
 from Standard.Base.Data.Time.Date as Date_Module import Date
-import Standard.Table.Io.Spreadsheet_Write_Mode
 import Standard.Table.Io.File_Format
 import Standard.Base.System.File
 import Standard.Base.System.File.Existing_File_Behavior
@@ -33,7 +32,6 @@ import Standard.Base.Data.Ordering.Comparator
 
 polyglot java import org.enso.table.data.table.Table as Java_Table
 polyglot java import org.enso.table.data.table.Column as Java_Column
-polyglot java import org.enso.table.format.xlsx.Writer as Spreadsheet_Writer
 polyglot java import org.enso.table.operations.OrderBuilder
 
 ## Creates a new table from a vector of `[name, items]` pairs.
@@ -1030,50 +1028,6 @@ type Table
         mask = OrderBuilder.buildReversedMask self.row_count
         Table <| self.java_table.applyMask mask
 
-    ## ALIAS Write Excel File
-       UNSTABLE
-
-       Writes this table into an XLSX spreadsheet.
-
-       Arguments:
-       - file: the XLSX file to write data to. If it exists, the behavior is
-         specified by the `write_mode` argument. Note that other files may be
-         created or written to if `max_rows_per_file` is used.
-       - sheet: the name of the sheet to use for writing the data.
-       - write_mode: specifies this method's behavior if the specified file and
-         sheet already exist. Can be one of:
-         - Spreadsheet_Write_Mode.Create: this is the default value. This
-           setting will create a new sheet in the file, with a name chosen such
-           that the clash is avoided.
-         - Spreadsheet_Write_Mode.Overwrite: will result in removing all
-           contents of the existing sheet and replacing it with the new data.
-         - Spreadsheet_Write_Mode.Append: will append this data to the existing
-           sheet, such that the new data starts after the last row containing
-           any data.
-       - include_header: Specifies whether the first line of generated CSV
-         should contain the column names.
-       - max_rows_per_file: specifies the maximum number of rows that can be
-         written to a single file. If this option is set and its value is less
-         than the number of rows in this table, the behavior of the `file`
-         argument changes. Instead of writing the contents directly to `file`,
-         its name is parsed and a numbered series of files with names based
-         on `file` is written to instead. For example, if `file` points to
-         `~/my_data/output.xlsx`, `self` contains 250 rows, and
-         `max_rows_per_file` is set to `100`, 3 different files will be written:
-         - `~/my_data/output_1.xlsx`, containing rows 0 through 99;
-         - `~/my_data/output_2.xlsx`, containing rows 100 through 199;
-         - `~/my_data/output_3.xlsx`, containing rows 200 through 249.
-
-       > Example
-         Write a table to an XLSX file.
-
-             import Standard.Examples
-
-             example_to_xlsx = Examples.inventory_table.write_xlsx (Enso_Project.data / example_xlsx_output.xlsx)
-    write_xlsx : File.File -> String -> Spreadsheet_Write_Mode.Speadsheet_Write_Mode -> Boolean -> Nothing | Integer -> Nothing
-    write_xlsx file sheet='Data' write_mode=Spreadsheet_Write_Mode.Create include_header=True max_rows_per_file=Nothing =
-        Spreadsheet_Writer.writeXlsx self.java_table file.absolute.path sheet write_mode.to_java include_header max_rows_per_file .write_to_spreadsheet
-
     ## ALIAS Write JSON
        UNSTABLE
 
@@ -1162,35 +1116,6 @@ type Table
     to_csv : Text
     to_csv = Text.from self (File_Format.Delimited delimiter=",")
 
-## UNSTABLE
-   ADVANCED
-
-   Used to write a value into a spreadsheet cell.
-
-   Arguments:
-   - cell: an instance of `org.apache.poi.ss.usermodel.Cell`, the value of
-     which should be set by this method.
-Any.write_to_spreadsheet cell = cell.setCellValue self.to_text
-
-## UNSTABLE
-   ADVANCED
-
-   Used to write a value into a spreadsheet cell.
-
-   Arguments:
-   - cell: an instance of `org.apache.poi.ss.usermodel.Cell`, the value of
-     which should be set by this method.
-Text.write_to_spreadsheet cell = cell.setCellValue self
-
-## UNSTABLE
-   ADVANCED
-
-   Used to write a value into a spreadsheet cell.
-
-   Arguments:
-   - cell: an instance of `org.apache.poi.ss.usermodel.Cell`, the value of
-     which should be set by this method.
-Date.write_to_spreadsheet cell = cell.setCellValue self.internal_local_date
 
 ## UNSTABLE
 

distribution/lib/Standard/Table/0.0.0-dev/src/Error.enso

@@ -174,3 +174,16 @@ type Unsupported_File_Type filename
 Unsupported_File_Type.to_display_text : Text
 Unsupported_File_Type.to_display_text =
     "The "+self.filename+" has a type that is not supported by the Auto format."
+
+## Indicates that the target range contains existing data and the user did not
+   specify to overwrite.
+type Existing_Data message
+
+Existing_Data.to_display_text : Text
+Existing_Data.to_display_text = self.message
+
+## Indicates that the specified range is not large enough to fit the data.
+type Range_Exceeded message
+
+Range_Exceeded.to_display_text : Text
+Range_Exceeded.to_display_text = self.message

distribution/lib/Standard/Table/0.0.0-dev/src/Io/Excel.enso

@@ -1,14 +1,23 @@
 from Standard.Base import all
 from Standard.Base.Error.Problem_Behavior as Problem_Behavior_Module import Problem_Behavior
+import Standard.Base.System.File.Existing_File_Behavior
+import Standard.Base.System.File.Option
 from Standard.Table.Io.File_Format import Infer
 
 import Standard.Table.Data.Table
-from Standard.Table.Error as Error_Module import Invalid_Location, Duplicate_Output_Column_Names, Invalid_Output_Column_Names
+from Standard.Table.Error as Error_Module import Invalid_Location, Duplicate_Output_Column_Names, Invalid_Output_Column_Names, Range_Exceeded, Existing_Data
+import Standard.Base.Error.Common as Errors
 
 polyglot java import org.enso.table.excel.ExcelRange as Java_Range
+polyglot java import org.enso.table.excel.ExcelHeaders
 polyglot java import org.enso.table.read.ExcelReader
+polyglot java import org.enso.table.write.ExcelWriter
+polyglot java import org.enso.table.error.ExistingDataException
+polyglot java import org.enso.table.error.RangeExceededException
+polyglot java import org.enso.table.error.InvalidLocationException
 
 polyglot java import java.lang.IllegalArgumentException
+polyglot java import java.lang.IllegalStateException
 polyglot java import java.io.IOException
 polyglot java import org.apache.poi.UnsupportedFileFormatException
 polyglot java import org.enso.table.util.problems.DuplicateNames
@@ -103,8 +112,9 @@ type Excel_Range
     ## Creates a Range from an address.
     from_address : Text -> Excel_Range
     from_address address =
-        Panic.catch IllegalArgumentException (Excel_Range (Java_Range.new address)) caught_panic->
+        illegal_argument caught_panic = Error.throw (Illegal_Argument_Error caught_panic.payload.cause.getMessage  caught_panic.payload.cause)
-            Error.throw (Illegal_Argument_Error caught_panic.payload.cause.getMessage caught_panic.payload.cause)
+        Panic.catch IllegalArgumentException handler=illegal_argument <|
+            Excel_Range (Java_Range.new address)
 
     ## Create a Range for a single cell.
     for_cell : Text -> (Text|Integer) -> Integer -> Excel_Range
@@ -185,16 +195,31 @@ read_excel file section headers on_problems xls_format=False =
                 Excel_Range _ -> ExcelReader.readRange stream address.java_range (here.make_java_headers headers) skip_rows row_limit xls_format
                 Text -> ExcelReader.readRangeByName stream address (here.make_java_headers headers) skip_rows row_limit xls_format
 
-    bad_argument caught_panic = Error.throw (Invalid_Location caught_panic.payload.cause.getCause)
+    here.read_excel_file file reader
-    handle_bad_argument = Panic.catch IllegalArgumentException handler=bad_argument
 
-    bad_format caught_panic = Error.throw (File.Io_Error file caught_panic.payload.cause.getMessage)
+write_excel : File -> Table -> Existing_File_Behavior -> (Sheet | Cell_Range) -> (Boolean|Infer) -> Problem_Behavior -> Boolean
-    handle_bad_format = Panic.catch UnsupportedFileFormatException handler=bad_format
+write_excel file table on_existing_file section headers _ xls_format=False =
+    if on_existing_file == Existing_File_Behavior.Append then Errors.unimplemented "Appending to an existing File_Format.Delimited file is not implemented yet." else
+        workbook = if file.exists.not then ExcelWriter.createWorkbook xls_format else
+            here.read_excel_file file stream->(ExcelReader.getWorkbook stream xls_format)
 
-    File.handle_java_exceptions file <| handle_bad_argument <| handle_bad_format <|
+        replace = (on_existing_file == Existing_File_Behavior.Overwrite) || (on_existing_file == Existing_File_Behavior.Backup)
-        file.with_input_stream [File.Option.Read] stream->(stream.with_java_stream reader)
+        java_headers = here.make_java_headers headers
+        if ExcelWriter.getEnsoToTextCallback == Nothing then ExcelWriter.getEnsoToTextCallback (.to_text)
+        result = here.handle_writer <| case section of
+            Sheet sheet skip_rows row_limit ->
+                ExcelWriter.writeTableToSheet workbook sheet replace skip_rows table.java_table row_limit java_headers
+            Cell_Range address skip_rows row_limit -> case address of
+                Excel_Range _ -> ExcelWriter.writeTableToRange workbook address.java_range replace skip_rows table.java_table row_limit java_headers
+                Text -> ExcelWriter.writeTableToRange workbook address replace skip_rows table.java_table row_limit java_headers
+
+        if result.is_error then result else
+            write_stream stream = stream.with_java_stream java_stream->
+                workbook.write java_stream
+            on_existing_file.write file write_stream
 
 ## PRIVATE
+prepare_reader_table : Problem_Behavior -> Any -> Table
 prepare_reader_table on_problems result_with_problems =
     map_problem java_problem =
         if Java.is_instance java_problem DuplicateNames then Duplicate_Output_Column_Names (Vector.Vector java_problem.duplicatedNames) else
@@ -204,9 +229,37 @@ prepare_reader_table on_problems result_with_problems =
     on_problems.attach_problems_after (Table.Table result_with_problems.value) parsing_problems
 
 ## PRIVATE
-   Convert True|False|Infer to the correct HeaderBehavior
+   Convert Boolean|Infer to the correct HeaderBehavior
-make_java_headers : (True|False|Infer) -> ExcelReader.HeaderBehavior
+make_java_headers : (Boolean|Infer) -> ExcelHeaders.HeaderBehavior
 make_java_headers headers = case headers of
-        True -> ExcelReader.HeaderBehavior.USE_FIRST_ROW_AS_HEADERS
+        True -> ExcelHeaders.HeaderBehavior.USE_FIRST_ROW_AS_HEADERS
-        Infer -> ExcelReader.HeaderBehavior.INFER
+        Infer -> ExcelHeaders.HeaderBehavior.INFER
-        False -> ExcelReader.HeaderBehavior.EXCEL_COLUMN_NAMES
+        False -> ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES
+
+## PRIVATE
+read_excel_file file reader =
+    bad_format caught_panic = Error.throw (File.Io_Error file caught_panic.payload.cause.getMessage)
+    handle_bad_format = Panic.catch UnsupportedFileFormatException handler=bad_format
+
+    bad_argument caught_panic = Error.throw (Invalid_Location caught_panic.payload.cause.getCause)
+    handle_bad_argument = Panic.catch InvalidLocationException handler=bad_argument
+
+    File.handle_java_exceptions file <| handle_bad_argument <| handle_bad_format <|
+        file.with_input_stream [File.Option.Read] stream->
+            stream.with_java_stream reader
+
+## PRIVATE
+handle_writer ~writer =
+    bad_location caught_panic = Error.throw (Invalid_Location caught_panic.payload.cause.getCause)
+    handle_bad_location = Panic.catch InvalidLocationException handler=bad_location
+
+    throw_range_exceeded caught_panic = Error.throw (Range_Exceeded caught_panic.payload.cause.getMessage)
+    handle_range_exceeded = Panic.catch RangeExceededException handler=throw_range_exceeded
+
+    throw_existing_data caught_panic = Error.throw (Existing_Data caught_panic.payload.cause.getMessage)
+    handle_existing_data = Panic.catch ExistingDataException handler=throw_existing_data
+
+    throw_illegal_state caught_panic = Panic.throw (Illegal_State_Error caught_panic.payload.cause.getMessage)
+    handle_illegal_state = Panic.catch IllegalStateException handler=throw_illegal_state
+
+    handle_illegal_state <| handle_bad_location <| handle_range_exceeded <| handle_existing_data <| writer

distribution/lib/Standard/Table/0.0.0-dev/src/Io/File_Format.enso

@@ -186,13 +186,22 @@ type Excel
     ## Implements the `File.read` for this `File_Format`
     read : File -> Problem_Behavior -> Any
     read file on_problems =
-        format = if self.xls_format != Infer then self.xls_format else
+        format = Excel.is_xls_format self.xls_format file
-            extension = file.extension
-            (extension.equals_ignore_case ".xls") || (extension.equals_ignore_case ".xlt")
-
         Excel_Module.read_excel file self.section self.headers on_problems format
 
     ## Implements the `Table.write` for this `File_Format`.
     write_table : File -> Table -> Existing_File_Behavior -> Column_Mapping -> Problem_Behavior -> Nothing
-    write_table _ _ _ _ _ =
+    write_table file table on_existing_file _ on_problems =
-        Errors.unimplemented "`Table.write` for the `Excel` format is not implemented yet."
+        format = Excel.is_xls_format self.xls_format file
+        case self.section of
+            Excel_Module.Sheet_Names -> Error.throw (Illegal_Argument_Error "Sheet_Names cannot be used for `write`.")
+            Excel_Module.Range_Names -> Error.throw (Illegal_Argument_Error "Range_Names cannot be used for `write`.")
+            _ -> Excel_Module.write_excel file table on_existing_file self.section self.headers on_problems format
+
+    ## PRIVATE
+       Resolve the xls_format setting to a boolean.
+    is_xls_format : (Boolean|Infer) -> File -> Boolean
+    is_xls_format xls_format file =
+        if xls_format != Infer then xls_format else
+            extension = file.extension
+            (extension.equals_ignore_case ".xls") || (extension.equals_ignore_case ".xlt")

distribution/lib/Standard/Table/0.0.0-dev/src/Io/Spreadsheet_Write_Mode.enso

@@ -1,24 +0,0 @@
-from Standard.Base import all
-
-polyglot java import org.enso.table.format.xlsx.Writer
-
-## Specifies the behavior of XLSX writing for pre-existing sheets.
-type Spreadsheet_Write_Mode
-    ## Append new data to the existing sheet, such that the new data starts
-       after the last row containing any data.
-    type Append
-    
-    ## Create a new sheet, renaming it such that there is no clash with
-       exisitng sheets.
-    type Create
-    
-    ## Remove all contents from the existing sheet and write the data to it.
-    type Overwrite
-
-    ## PRIVATE
-
-       Converts this into a Java-side representation.
-    to_java = case self of
-        Append -> Writer.WriteMode.APPEND
-        Create -> Writer.WriteMode.CREATE_SHEET
-        Overwrite -> Writer.WriteMode.OVERWRITE_SHEET

distribution/lib/Standard/Table/0.0.0-dev/src/Main.enso

@@ -2,18 +2,18 @@ from Standard.Base import all
 
 import Standard.Geo.Geo_Json
 import Standard.Table.Io.File_Read
+import Standard.Table.Io.File_Format
 import Standard.Table.Io.Excel
-import Standard.Table.Io.Spreadsheet_Write_Mode
 import Standard.Table.Data.Table
 import Standard.Table.Data.Column
 import Standard.Table.Model
 
 from Standard.Table.Io.Excel export Excel_Section, Excel_Range
 
-export Standard.Table.Io.Spreadsheet_Write_Mode
 export Standard.Table.Data.Column
 export Standard.Table.Model
 export Standard.Table.Io.File_Read
+export Standard.Table.Io.File_Format
 
 from Standard.Table.Data.Table export new, from_rows, join, concat, No_Such_Column_Error, Table
 

engine/runtime/src/main/java/org/enso/interpreter/runtime/data/EnsoFile.java

@@ -138,6 +138,12 @@ public class EnsoFile implements TruffleObject {
     truffleFile.delete();
   }
 
+  @Builtin.Method(name = "copy_builtin", description = "Copy this file to a target destination")
+  @Builtin.WrapException(from = IOException.class, to = PolyglotError.class, propagate = true)
+  public void copy(EnsoFile target, CopyOption[] options) throws IOException {
+    truffleFile.copy(target.truffleFile, options);
+  }
+
   @Builtin.Method(name = "move_builtin", description = "Move this file to a target destination")
   @Builtin.WrapException(from = IOException.class, to = PolyglotError.class, propagate = true)
   public void move(EnsoFile target, CopyOption[] options) throws IOException {

std-bits/table/src/main/java/org/enso/table/data/column/storage/BoolStorage.java

@@ -2,10 +2,7 @@ package org.enso.table.data.column.storage;
 
 import java.util.BitSet;
 import java.util.Comparator;
-import java.util.function.BiConsumer;
-import java.util.function.Function;
 
-import org.apache.poi.ss.usermodel.Cell;
 import org.enso.table.data.column.operation.map.MapOpStorage;
 import org.enso.table.data.column.operation.map.MapOperation;
 import org.enso.table.data.column.operation.map.UnaryMapOperation;
@@ -320,9 +317,4 @@ public class BoolStorage extends Storage {
         newSize,
         negated);
   }
-
-  @Override
-  public void writeSpreadsheetCell(int index, Cell cell, BiConsumer<Object, Cell> writeCell) {
-    cell.setCellValue(getItem(index));
-  }
 }

std-bits/table/src/main/java/org/enso/table/data/column/storage/DoubleStorage.java

@@ -2,10 +2,7 @@ package org.enso.table.data.column.storage;
 
 import java.util.BitSet;
 import java.util.Comparator;
-import java.util.function.BiConsumer;
-import java.util.function.Function;
 
-import org.apache.poi.ss.usermodel.Cell;
 import org.enso.table.data.column.builder.object.NumericBuilder;
 import org.enso.table.data.column.operation.map.MapOpStorage;
 import org.enso.table.data.column.operation.map.UnaryMapOperation;
@@ -268,9 +265,4 @@ public class DoubleStorage extends NumericStorage {
     BitSet newMask = isMissing.get(offset, offset + limit);
     return new DoubleStorage(newData, newSize, newMask);
   }
-
-  @Override
-  public void writeSpreadsheetCell(int index, Cell cell, BiConsumer<Object, Cell> writeCell) {
-    cell.setCellValue(getItem(index));
-  }
 }

std-bits/table/src/main/java/org/enso/table/data/column/storage/LongStorage.java

@@ -1,11 +1,8 @@
 package org.enso.table.data.column.storage;
 
 import java.util.*;
-import java.util.function.BiConsumer;
-import java.util.function.Function;
 import java.util.stream.LongStream;
 
-import org.apache.poi.ss.usermodel.Cell;
 import org.enso.table.data.column.builder.object.NumericBuilder;
 import org.enso.table.data.column.operation.aggregate.Aggregator;
 import org.enso.table.data.column.operation.aggregate.numeric.LongToLongAggregator;
@@ -98,46 +95,42 @@ public class LongStorage extends NumericStorage {
 
   @Override
   protected Aggregator getVectorizedAggregator(String name, int resultSize) {
-    switch (name) {
+    return switch (name) {
-      case Aggregators.SUM:
+      case Aggregators.SUM -> new LongToLongAggregator(this, resultSize) {
-        return new LongToLongAggregator(this, resultSize) {
+        @Override
-          @Override
+        protected void runGroup(LongStream items) {
-          protected void runGroup(LongStream items) {
+          long[] elements = items.toArray();
-            long[] elements = items.toArray();
+          if (elements.length == 0) {
-            if (elements.length == 0) {
+            submitMissing();
-              submitMissing();
+          } else {
-            } else {
+            submit(LongStream.of(elements).sum());
-              submit(LongStream.of(elements).sum());
-            }
           }
-        };
+        }
-      case Aggregators.MAX:
+      };
-        return new LongToLongAggregator(this, resultSize) {
+      case Aggregators.MAX -> new LongToLongAggregator(this, resultSize) {
-          @Override
+        @Override
-          protected void runGroup(LongStream items) {
+        protected void runGroup(LongStream items) {
-            OptionalLong r = items.max();
+          OptionalLong r = items.max();
-            if (r.isPresent()) {
+          if (r.isPresent()) {
-              submit(r.getAsLong());
+            submit(r.getAsLong());
-            } else {
+          } else {
-              submitMissing();
+            submitMissing();
-            }
           }
-        };
+        }
-      case Aggregators.MIN:
+      };
-        return new LongToLongAggregator(this, resultSize) {
+      case Aggregators.MIN -> new LongToLongAggregator(this, resultSize) {
-          @Override
+        @Override
-          protected void runGroup(LongStream items) {
+        protected void runGroup(LongStream items) {
-            OptionalLong r = items.min();
+          OptionalLong r = items.min();
-            if (r.isPresent()) {
+          if (r.isPresent()) {
-              submit(r.getAsLong());
+            submit(r.getAsLong());
-            } else {
+          } else {
-              submitMissing();
+            submitMissing();
-            }
           }
-        };
+        }
-      default:
+      };
-        return super.getVectorizedAggregator(name, resultSize);
+      default -> super.getVectorizedAggregator(name, resultSize);
-    }
+    };
   }
 
   private Storage fillMissingDouble(double arg) {
@@ -382,9 +375,4 @@ public class LongStorage extends NumericStorage {
     BitSet newMask = isMissing.get(offset, offset + limit);
     return new LongStorage(newData, newSize, newMask);
   }
-
-  @Override
-  public void writeSpreadsheetCell(int index, Cell cell, BiConsumer<Object, Cell> writeCell) {
-    cell.setCellValue(getItem(index));
-  }
 }

std-bits/table/src/main/java/org/enso/table/data/column/storage/ObjectStorage.java

@@ -1,17 +1,13 @@
 package org.enso.table.data.column.storage;
 
-import java.util.Arrays;
-import java.util.BitSet;
-import java.util.Comparator;
-import java.util.function.BiConsumer;
-import java.util.function.Function;
-
-import org.apache.poi.ss.usermodel.Cell;
 import org.enso.table.data.column.operation.map.MapOpStorage;
 import org.enso.table.data.column.operation.map.UnaryMapOperation;
 import org.enso.table.data.index.Index;
 import org.enso.table.data.mask.OrderMask;
 
+import java.util.BitSet;
+import java.util.Comparator;
+
 /** A column storing arbitrary objects. */
 public class ObjectStorage extends Storage {
   private final Object[] data;
@@ -157,9 +153,4 @@ public class ObjectStorage extends Storage {
     System.arraycopy(data, offset, newData, 0, newSize);
     return new ObjectStorage(newData, newSize);
   }
-
-  @Override
-  public void writeSpreadsheetCell(int index, Cell cell, BiConsumer<Object, Cell> writeCell) {
-    writeCell.accept(getItem(index), cell);
-  }
 }

std-bits/table/src/main/java/org/enso/table/data/column/storage/Storage.java

@@ -1,6 +1,5 @@
 package org.enso.table.data.column.storage;
 
-import org.apache.poi.ss.usermodel.Cell;
 import org.enso.table.data.column.builder.object.Builder;
 import org.enso.table.data.column.builder.object.InferredBuilder;
 import org.enso.table.data.column.operation.aggregate.Aggregator;
@@ -8,7 +7,6 @@ import org.enso.table.data.column.operation.aggregate.CountAggregator;
 import org.enso.table.data.column.operation.aggregate.FunctionAggregator;
 
 import java.util.*;
-import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import java.util.function.Function;
 
@@ -297,14 +295,4 @@ public abstract class Storage {
     }
     return new LongStorage(data);
   }
-
-  /**
-   * Write the value at the specified index into an XLSX cell.
-   *
-   * @param index the index to read value at. {@link #isNa(long)} must return false for this index.
-   * @param cell the cell to write data to
-   * @param writeCell a callback to delegate writes back to Enso code
-   */
-  public abstract void writeSpreadsheetCell(
-      int index, Cell cell, BiConsumer<Object, Cell> writeCell);
 }

std-bits/table/src/main/java/org/enso/table/data/column/storage/StringStorage.java

@@ -2,9 +2,6 @@ package org.enso.table.data.column.storage;
 
 import java.util.BitSet;
 import java.util.Comparator;
-import java.util.function.BiConsumer;
-import java.util.function.Function;
-import org.apache.poi.ss.usermodel.Cell;
 import org.enso.table.data.column.builder.object.StringBuilder;
 import org.enso.table.data.column.operation.map.MapOpStorage;
 import org.enso.table.data.column.operation.map.MapOperation;
@@ -71,7 +68,7 @@ public class StringStorage extends ObjectStorage {
   @Override
   public StringStorage applyMask(OrderMask mask) {
     ObjectStorage storage = super.applyMask(mask);
-    return new StringStorage(storage.getData(), (int) storage.size());
+    return new StringStorage(storage.getData(), storage.size());
   }
 
   @Override
@@ -146,9 +143,4 @@ public class StringStorage extends ObjectStorage {
     ObjectStorage storage = super.slice(offset, limit);
     return new StringStorage(storage.getData(), storage.size());
   }
-
-  @Override
-  public void writeSpreadsheetCell(int index, Cell cell, BiConsumer<Object, Cell> writeCell) {
-    cell.setCellValue(getItem(index));
-  }
 }

std-bits/table/src/main/java/org/enso/table/error/ExistingDataException.java

@@ -0,0 +1,7 @@
+package org.enso.table.error;
+
+public class ExistingDataException extends Exception {
+  public ExistingDataException(String errorMessage) {
+    super(errorMessage);
+  }
+}

std-bits/table/src/main/java/org/enso/table/error/InvalidLocationException.java

@@ -0,0 +1,7 @@
+package org.enso.table.error;
+
+public class InvalidLocationException extends Exception {
+  public InvalidLocationException(String errorMessage) {
+    super(errorMessage);
+  }
+}

std-bits/table/src/main/java/org/enso/table/error/RangeExceededException.java

@@ -0,0 +1,7 @@
+package org.enso.table.error;
+
+public class RangeExceededException extends Exception {
+  public RangeExceededException(String errorMessage) {
+    super(errorMessage);
+  }
+}

std-bits/table/src/main/java/org/enso/table/excel/ExcelHeaders.java

@@ -5,7 +5,6 @@ import org.apache.poi.ss.usermodel.CellType;
 import org.apache.poi.ss.usermodel.DataFormatter;
 import org.apache.poi.ss.util.CellReference;
 import org.enso.table.problems.Problem;
-import org.enso.table.read.ExcelReader;
 import org.enso.table.util.NameDeduplicator;
 
 import java.util.List;
@@ -15,7 +14,7 @@ public class ExcelHeaders {
   private final int startCol;
   private final String[] names;
 
-  public ExcelHeaders(ExcelReader.HeaderBehavior headers, ExcelRow startRow, ExcelRow nextRow, int startCol, int endCol) {
+  public ExcelHeaders(HeaderBehavior headers, ExcelRow startRow, ExcelRow nextRow, int startCol, int endCol) {
     deduplicator = new NameDeduplicator();
 
     this.startCol = startCol;
@@ -75,32 +74,27 @@ public class ExcelHeaders {
       return null;
     }
 
-    String[] rowNames = getCellsAsText(row, startCol, endCol);
+    String[] rowNames = row.getCellsAsText(startCol, endCol);
     if (rowNames == null) {
       return null;
     }
 
-    String[] nextNames = getCellsAsText(nextRow, startCol, endCol);
+    if (nextRow.getCellsAsText(startCol, endCol) != null) {
-    if (nextNames != null) {
       return null;
     }
 
     return deduplicator.makeUnique(rowNames);
   }
 
-  private static String[] getCellsAsText(ExcelRow row, int startCol, int endCol) {
+  /** Specifies how to set the headers for the returned table. */
-    int currentEndCol = endCol == -1 ? row.getLastColumn() : endCol;
+  public enum HeaderBehavior {
+    /** Tries to infer if the headers are present in the file. */
+    INFER,
 
-    String[] output = new String[currentEndCol - startCol + 1];
+    /** Uses the first row in the file as headers. Duplicate names will be appended suffixes. */
-    for (int col = startCol; col <= currentEndCol; col++) {
+    USE_FIRST_ROW_AS_HEADERS,
-      Cell cell = row.get(col);
-      CellType type = ExcelRow.getCellType(cell);
-      if (type != CellType._NONE && type != CellType.STRING) {
-        return null;
-      }
-      output[col - startCol] = type == CellType.STRING && cell != null ? cell.getStringCellValue() : "";
-    }
 
-    return output;
+    /** Uses the default Excel Column Names (e.g. A, B, C). */
+    EXCEL_COLUMN_NAMES
   }
 }

std-bits/table/src/main/java/org/enso/table/excel/ExcelRange.java

@@ -1,5 +1,6 @@
 package org.enso.table.excel;
 
+import org.apache.poi.ss.usermodel.CellType;
 import org.apache.poi.ss.util.CellReference;
 
 import java.util.Optional;
@@ -147,15 +148,67 @@ public class ExcelRange {
     return parsed.value;
   }
 
+  /**
+   * Create an ExcelRange for a given set of columns.
+   *
+   * @param sheetName name of the containing sheet.
+   * @param leftColumn left-hand column index (1-based).
+   * @param rightColumn inclusive right-hand column index (1-based).
+   * @return ExcelRange for the given columns.
+   */
   public static ExcelRange forColumns(String sheetName, int leftColumn, int rightColumn) {
     return new ExcelRange(
         sheetName, leftColumn, WHOLE_ROW_OR_COLUMN, rightColumn, WHOLE_ROW_OR_COLUMN);
   }
 
+  /**
+   * Create an ExcelRange for a given set of rows.
+   *
+   * @param sheetName name of the containing sheet.
+   * @param topRow top row index (1-based).
+   * @param bottomRow inclusive bottom row index (1-based).
+   * @return ExcelRange for the given rows.
+   */
   public static ExcelRange forRows(String sheetName, int topRow, int bottomRow) {
     return new ExcelRange(sheetName, WHOLE_ROW_OR_COLUMN, topRow, WHOLE_ROW_OR_COLUMN, bottomRow);
   }
 
+  /**
+   * Given a single cell and the containing sheet, expand the range to cover the connected table of
+   * cells.
+   *
+   * @param excelRange Range referring to top left cell.
+   * @param sheet ExcelSheet containing the range refers to.
+   * @return Expanded range covering the connected table of cells.
+   */
+  public static ExcelRange expandSingleCell(ExcelRange excelRange, ExcelSheet sheet) {
+    ExcelRow currentRow = sheet.get(excelRange.getTopRow());
+    if (currentRow == null || currentRow.isEmpty(excelRange.getLeftColumn())) {
+      return new ExcelRange(
+          excelRange.getSheetName(),
+          excelRange.getLeftColumn(),
+          excelRange.getTopRow(),
+          excelRange.getLeftColumn(),
+          excelRange.getTopRow());
+    }
+
+    int bottomRow = excelRange.getTopRow();
+    int rightColumn = excelRange.getLeftColumn();
+
+    while (currentRow != null && !currentRow.isEmpty(excelRange.getLeftColumn(), rightColumn)) {
+      rightColumn = currentRow.findEndRight(rightColumn);
+      bottomRow++;
+      currentRow = sheet.get(bottomRow);
+    }
+
+    return new ExcelRange(
+        excelRange.getSheetName(),
+        excelRange.getLeftColumn(),
+        excelRange.getTopRow(),
+        rightColumn,
+        bottomRow - 1);
+  }
+
   /**
    * @param index Index to the next character after the parsed value
    * @param value Parsed integer value or 0 if not valid
@@ -251,6 +304,10 @@ public class ExcelRange {
     return rightColumn;
   }
 
+  public int getColumnCount() {
+    return isWholeRow() ? Integer.MAX_VALUE : rightColumn - leftColumn + 1;
+  }
+
   public boolean isWholeColumn() {
     return topRow == WHOLE_ROW_OR_COLUMN;
   }
@@ -263,6 +320,10 @@ public class ExcelRange {
     return bottomRow;
   }
 
+  public int getRowCount() {
+    return isWholeColumn() ? Integer.MAX_VALUE : bottomRow - topRow + 1;
+  }
+
   public boolean isSingleCell() {
     return this.singleCell;
   }

std-bits/table/src/main/java/org/enso/table/excel/ExcelRow.java

@@ -37,7 +37,12 @@ public class ExcelRow {
         if (DateUtil.isCellDateFormatted(cell)) {
           return cell.getLocalDateTimeCellValue().toLocalDate();
         } else {
-          return cell.getNumericCellValue();
+          double dblValue = cell.getNumericCellValue();
+          if (dblValue == (long) dblValue) {
+            return (long) dblValue;
+          } else {
+            return dblValue;
+          }
         }
       case STRING:
         return cell.getStringCellValue();
@@ -62,12 +67,14 @@ public class ExcelRow {
   }
 
   public boolean isEmpty(int column) {
-    return isEmpty(column, column);
+    CellType cellType = getCellType(get(column));
+    return (cellType == CellType._NONE) || (cellType == CellType.BLANK);
   }
 
   public boolean isEmpty(int start, int end) {
-    for (int column = start; column <= end; column++) {
+    int currentEnd = end == -1 ? getLastColumn() : end;
-      if (getCellType(get(column)) != CellType._NONE) {
+    for (int column = start; column <= currentEnd; column++) {
+      if (!isEmpty(column)) {
         return false;
       }
     }
@@ -76,9 +83,26 @@ public class ExcelRow {
 
   public int findEndRight(int start) {
     int column = start;
-    while (getCellType(get(column + 1)) != CellType._NONE) {
+    while (!isEmpty(column + 1)) {
       column++;
     }
     return column;
   }
+
+  public String[] getCellsAsText(int startCol, int endCol) {
+    int currentEndCol = endCol == -1 ? getLastColumn() : endCol;
+
+    String[] output = new String[currentEndCol - startCol + 1];
+    for (int col = startCol; col <= currentEndCol; col++) {
+      Cell cell = get(col);
+      CellType type = ExcelRow.getCellType(cell);
+      if (type != CellType._NONE && type != CellType.BLANK && type != CellType.STRING) {
+        return null;
+      }
+      output[col - startCol] =
+          type == CellType.STRING && cell != null ? cell.getStringCellValue() : "";
+    }
+
+    return output;
+  }
 }

std-bits/table/src/main/java/org/enso/table/excel/ExcelSheet.java

@@ -28,4 +28,8 @@ public class ExcelSheet {
     Row underlyingRow = row < firstRow || row > lastRow ? null : sheet.getRow(row - 1);
     return underlyingRow == null ? null : new ExcelRow(underlyingRow);
   }
+
+  public Sheet getSheet() {
+    return sheet;
+  }
 }

std-bits/table/src/main/java/org/enso/table/format/xlsx/Writer.java

@@ -1,189 +0,0 @@
-package org.enso.table.format.xlsx;
-
-import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
-import org.apache.poi.ss.usermodel.Cell;
-import org.apache.poi.ss.usermodel.CellType;
-import org.apache.poi.ss.usermodel.Sheet;
-import org.apache.poi.ss.usermodel.Workbook;
-import org.apache.poi.xssf.usermodel.XSSFWorkbook;
-import org.enso.table.data.table.Table;
-import org.enso.table.format.util.FileSplitter;
-
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.util.Arrays;
-import java.util.function.BiConsumer;
-
-/** Writer for XLSX files. */
-public class Writer {
-  /** Specifies write behavior for files that already exist. */
-  public enum WriteMode {
-    /** Append new contents to the existing sheet. */
-    APPEND,
-    /** Remove old contents and replace with new. */
-    OVERWRITE_SHEET,
-    /** Create a new sheet, avoiding a name clash. */
-    CREATE_SHEET
-  }
-
-  /**
-   * Write a table to XLSX.
-   *
-   * @param table the table
-   * @param path the path to the xlsx file
-   * @param sheetName the name of the sheet
-   * @param writeMode specification of this function's behavior when the specified sheet already
-   *     exists
-   * @param writeHeader whether the first row should contain column names
-   * @param maxRecords the max number of records that can be written to a single file
-   * @param writeCell a helper for writing arbitrary objects into XLSX cells.
-   * @throws IOException when any of the files cannot be read.
-   * @throws InvalidFormatException when the specified file exists, but is not an XLSX file.
-   */
-  public static void writeXlsx(
-      Table table,
-      String path,
-      String sheetName,
-      WriteMode writeMode,
-      boolean writeHeader,
-      Integer maxRecords,
-      BiConsumer<Object, Cell> writeCell)
-      throws IOException, InvalidFormatException {
-    if (maxRecords == null || maxRecords >= table.rowCount()) {
-      var file = new File(path);
-      writeXlsx(table, file, sheetName, writeMode, writeHeader, 0, table.rowCount(), writeCell);
-    } else {
-      var splitter = new FileSplitter(table.rowCount(), maxRecords, new File(path));
-      for (int i = 0; i < splitter.getNumberOfFiles(); i++) {
-        writeXlsx(
-            table,
-            splitter.getFile(i),
-            sheetName,
-            writeMode,
-            writeHeader,
-            i * maxRecords,
-            maxRecords,
-            writeCell);
-      }
-    }
-  }
-
-  private static Workbook workbookForFile(File file) throws IOException, InvalidFormatException {
-    if (file.exists()) {
-      try (var stream = new FileInputStream(file)) {
-        return new XSSFWorkbook(stream);
-      }
-    } else {
-      return new XSSFWorkbook();
-    }
-  }
-
-  private static void writeXlsx(
-      Table table,
-      File file,
-      String sheetName,
-      WriteMode writeMode,
-      boolean writeHeader,
-      int startRecord,
-      int numRecords,
-      BiConsumer<Object, Cell> writeCell)
-      throws IOException, InvalidFormatException {
-    try (var workbook = workbookForFile(file)) {
-      writeWorkbook(
-          table, workbook, sheetName, writeMode, writeHeader, startRecord, numRecords, writeCell);
-      try (var outputStream = new FileOutputStream(file)) {
-        workbook.write(outputStream);
-      }
-    }
-  }
-
-  private static void writeWorkbook(
-      Table table,
-      Workbook workbook,
-      String sheetName,
-      WriteMode writeMode,
-      boolean writeHeader,
-      int startRecord,
-      int numRecords,
-      BiConsumer<Object, Cell> writeCell) {
-    var sheet = workbook.getSheet(sheetName);
-    if (sheet == null) {
-      var newSheet = workbook.createSheet(sheetName);
-      writeSheet(table, newSheet, writeHeader, startRecord, numRecords, 0, 0, writeCell);
-      return;
-    }
-    switch (writeMode) {
-      case APPEND:
-        writeSheet(
-            table,
-            sheet,
-            writeHeader,
-            startRecord,
-            numRecords,
-            sheet.getLastRowNum() + 1,
-            0,
-            writeCell);
-        workbook.setForceFormulaRecalculation(true);
-        return;
-      case OVERWRITE_SHEET:
-        int row;
-        while ((row = sheet.getLastRowNum()) != -1) {
-          sheet.removeRow(sheet.getRow(row));
-        }
-        writeSheet(table, sheet, writeHeader, startRecord, numRecords, 0, 0, writeCell);
-        workbook.setForceFormulaRecalculation(true);
-        return;
-      case CREATE_SHEET:
-        int currentSheet = 1;
-        var newSheetName = "";
-        do {
-          newSheetName = sheetName + " " + currentSheet;
-          sheet = workbook.getSheet(newSheetName);
-          currentSheet++;
-        } while (sheet != null);
-        sheet = workbook.createSheet(newSheetName);
-        writeSheet(table, sheet, writeHeader, startRecord, numRecords, 0, 0, writeCell);
-        workbook.setForceFormulaRecalculation(true);
-        return;
-    }
-  }
-
-  private static void writeSheet(
-      Table table,
-      Sheet sheet,
-      boolean writeHeader,
-      int startRecord,
-      int numRecords,
-      int startRow,
-      int startCol,
-      BiConsumer<Object, Cell> writeCell) {
-    var columns = Arrays.asList(table.getColumns());
-    var index = table.getIndex().toColumn();
-    if (index != null) {
-      columns.add(0, index);
-    }
-    if (writeHeader) {
-      var row = sheet.createRow(startRow);
-      startRow++;
-      for (int j = 0; j < columns.size(); j++) {
-        var cell = row.createCell(startCol + j, CellType.STRING);
-        cell.setCellValue(columns.get(j).getName());
-      }
-    }
-    var rowLimit = Math.min(numRecords, table.rowCount() - startRecord);
-    for (int i = 0; i < rowLimit; i++) {
-      var row = sheet.createRow(startRow + i);
-      for (int j = 0; j < columns.size(); j++) {
-        var cell = row.createCell(startCol + j);
-        var storage = columns.get(j).getStorage();
-        if (storage.isNa(startRecord + i)) {
-          cell.setBlank();
-        } else {
-          storage.writeSpreadsheetCell(startRecord + i, cell, writeCell);
-        }
-      }
-    }
-  }
-}

std-bits/table/src/main/java/org/enso/table/read/ExcelReader.java

@@ -1,7 +1,8 @@
 package org.enso.table.read;
 
 import org.apache.poi.hssf.usermodel.HSSFWorkbook;
-import org.apache.poi.ss.usermodel.*;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.ss.usermodel.Name;
 import org.apache.poi.ss.util.CellReference;
 import org.apache.poi.xssf.usermodel.XSSFWorkbook;
 import org.enso.table.data.column.builder.object.Builder;
@@ -9,6 +10,7 @@ import org.enso.table.data.column.builder.object.InferredBuilder;
 import org.enso.table.data.column.storage.ObjectStorage;
 import org.enso.table.data.table.Column;
 import org.enso.table.data.table.Table;
+import org.enso.table.error.InvalidLocationException;
 import org.enso.table.excel.ExcelHeaders;
 import org.enso.table.excel.ExcelRange;
 import org.enso.table.excel.ExcelRow;
@@ -67,20 +69,21 @@ public class ExcelReader {
    * @param xls_format specifies whether the file is in Excel Binary Format (95-2003 format).
    * @return a {@link Table} containing the specified data.
    * @throws IOException when the input stream cannot be read.
+   * @throws InvalidLocationException when the sheet name is not found.
    */
   public static WithProblems<Table> readSheetByName(
       InputStream stream,
       String sheetName,
-      HeaderBehavior headers,
+      ExcelHeaders.HeaderBehavior headers,
       int skip_rows,
       Integer row_limit,
       boolean xls_format)
-      throws IOException, IllegalArgumentException {
+      throws IOException, InvalidLocationException {
     Workbook workbook = getWorkbook(stream, xls_format);
 
-    int sheetIndex = getSheetIndex(workbook, sheetName);
+    int sheetIndex = workbook.getSheetIndex(sheetName);
     if (sheetIndex == -1) {
-      throw new IllegalArgumentException("Unknown sheet '" + sheetName + "'.");
+      throw new InvalidLocationException("Unknown sheet '" + sheetName + "'.");
     }
 
     return readTable(
@@ -102,20 +105,21 @@ public class ExcelReader {
    * @param xls_format specifies whether the file is in Excel Binary Format (95-2003 format).
    * @return a {@link Table} containing the specified data.
    * @throws IOException when the input stream cannot be read.
+   * @throws InvalidLocationException when the sheet index is not valid.
    */
   public static WithProblems<Table> readSheetByIndex(
       InputStream stream,
       int index,
-      HeaderBehavior headers,
+      ExcelHeaders.HeaderBehavior headers,
       int skip_rows,
       Integer row_limit,
       boolean xls_format)
-      throws IOException, IllegalArgumentException {
+      throws IOException, InvalidLocationException {
     Workbook workbook = getWorkbook(stream, xls_format);
 
     int sheetCount = workbook.getNumberOfSheets();
     if (index < 1 || index > sheetCount) {
-      throw new IllegalArgumentException(
+      throw new InvalidLocationException(
           "Sheet index is not in valid range (1 to " + sheetCount + " inclusive).");
     }
 
@@ -138,20 +142,28 @@ public class ExcelReader {
    * @param xls_format specifies whether the file is in Excel Binary Format (95-2003 format).
    * @return a {@link Table} containing the specified data.
    * @throws IOException when the input stream cannot be read.
+   * @throws InvalidLocationException when the range name or address is not found.
    */
   public static WithProblems<Table> readRangeByName(
       InputStream stream,
       String rangeNameOrAddress,
-      HeaderBehavior headers,
+      ExcelHeaders.HeaderBehavior headers,
       int skip_rows,
       Integer row_limit,
       boolean xls_format)
-      throws IOException {
+      throws IOException, InvalidLocationException {
     Workbook workbook = getWorkbook(stream, xls_format);
 
     Name name = workbook.getName(rangeNameOrAddress);
-    ExcelRange excelRange =
+
-        new ExcelRange(name == null ? rangeNameOrAddress : name.getRefersToFormula());
+    ExcelRange excelRange;
+    try {
+      excelRange = new ExcelRange(name == null ? rangeNameOrAddress : name.getRefersToFormula());
+    } catch (IllegalArgumentException e) {
+      throw new InvalidLocationException(
+          "Invalid range name or address '" + rangeNameOrAddress + "'.");
+    }
+
     return readRange(workbook, excelRange, headers, skip_rows, row_limit);
   }
 
@@ -169,39 +181,36 @@ public class ExcelReader {
   public static WithProblems<Table> readRange(
       InputStream stream,
       ExcelRange excelRange,
-      HeaderBehavior headers,
+      ExcelHeaders.HeaderBehavior headers,
       int skip_rows,
       Integer row_limit,
       boolean xls_format)
-      throws IOException {
+      throws IOException, InvalidLocationException {
     return readRange(getWorkbook(stream, xls_format), excelRange, headers, skip_rows, row_limit);
   }
 
-  /** Specifies how to set the headers for the returned table. */
+  /**
-  public enum HeaderBehavior {
+   * Load a workbook into memory from an InputStream.
-    /** Tries to infer if the headers are present in the file. */
+   *
-    INFER,
+   * @param stream an {@link InputStream} allowing to read the XLSX file contents.
-
+   * @param xls_format specifies whether the file is in Excel Binary Format (95-2003 format).
-    /** Uses the first row in the file as headers. Duplicate names will be appended suffixes. */
+   * @return a {@link Workbook} containing the specified data.
-    USE_FIRST_ROW_AS_HEADERS,
+   * @throws IOException when the input stream cannot be read or an incorrect format occurs.
-
+   */
-    /** Uses the default Excel Column Names (e.g. A, B, C). */
+  public static Workbook getWorkbook(InputStream stream, boolean xls_format) throws IOException {
-    EXCEL_COLUMN_NAMES
-  }
-
-  private static Workbook getWorkbook(InputStream stream, boolean xls_format) throws IOException {
     return xls_format ? new HSSFWorkbook(stream) : new XSSFWorkbook(stream);
   }
 
   private static WithProblems<Table> readRange(
       Workbook workbook,
       ExcelRange excelRange,
-      HeaderBehavior headers,
+      ExcelHeaders.HeaderBehavior headers,
       int skip_rows,
-      Integer row_limit) {
+      Integer row_limit)
-    int sheetIndex = getSheetIndex(workbook, excelRange.getSheetName());
+      throws InvalidLocationException {
+    int sheetIndex = workbook.getSheetIndex(excelRange.getSheetName());
     if (sheetIndex == -1) {
-      throw new IllegalArgumentException("Unknown sheet '" + excelRange.getSheetName() + "'.");
+      throw new InvalidLocationException("Unknown sheet '" + excelRange.getSheetName() + "'.");
     }
 
     return readTable(
@@ -217,7 +226,7 @@ public class ExcelReader {
       Workbook workbook,
       int sheetIndex,
       ExcelRange excelRange,
-      HeaderBehavior headers,
+      ExcelHeaders.HeaderBehavior headers,
       int skipRows,
       int rowCount) {
     ExcelSheet sheet = new ExcelSheet(workbook, sheetIndex);
@@ -236,7 +245,7 @@ public class ExcelReader {
             Collections.emptyList());
       }
 
-      excelRange = expandSingleCell(excelRange, sheet, currentRow);
+      excelRange = ExcelRange.expandSingleCell(excelRange, sheet);
     }
 
     // Row Range
@@ -306,26 +315,6 @@ public class ExcelReader {
     return new WithProblems<>(new Table(columns), excelHeaders.getProblems());
   }
 
-  private static ExcelRange expandSingleCell(
-      ExcelRange excelRange, ExcelSheet sheet, ExcelRow currentRow) {
-    int bottomRow = excelRange.getTopRow();
-    int rightColumn = excelRange.getLeftColumn();
-    while (currentRow != null && !currentRow.isEmpty(excelRange.getLeftColumn(), rightColumn)) {
-      rightColumn = currentRow.findEndRight(rightColumn);
-      bottomRow++;
-      currentRow = sheet.get(bottomRow);
-    }
-
-    excelRange =
-        new ExcelRange(
-            excelRange.getSheetName(),
-            excelRange.getLeftColumn(),
-            excelRange.getTopRow(),
-            rightColumn,
-            bottomRow - 1);
-    return excelRange;
-  }
-
   private static void expandBuilders(List<Builder> builders, int size, int columnCount, int rows) {
     for (int i = builders.size(); i <= columnCount; i++) {
       Builder builder = new InferredBuilder(size);
@@ -333,14 +322,4 @@ public class ExcelReader {
       builders.add(builder);
     }
   }
-
-  private static int getSheetIndex(Workbook workbook, String sheetName) {
-    int sheetCount = workbook.getNumberOfSheets();
-    for (int i = 0; i < sheetCount; i++) {
-      if (workbook.getSheetName(i).equalsIgnoreCase(sheetName)) {
-        return i;
-      }
-    }
-    return -1;
-  }
 }

std-bits/table/src/main/java/org/enso/table/write/ExcelWriter.java

@@ -0,0 +1,324 @@
+package org.enso.table.write;
+
+import org.apache.poi.hssf.usermodel.HSSFWorkbook;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Name;
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.CellStyle;
+import org.apache.poi.ss.usermodel.CellType;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.enso.table.data.column.storage.BoolStorage;
+import org.enso.table.data.column.storage.DoubleStorage;
+import org.enso.table.data.column.storage.LongStorage;
+import org.enso.table.data.column.storage.Storage;
+import org.enso.table.data.table.Column;
+import org.enso.table.data.table.Table;
+import org.enso.table.error.ExistingDataException;
+import org.enso.table.error.RangeExceededException;
+import org.enso.table.error.InvalidLocationException;
+import org.enso.table.excel.ExcelHeaders;
+import org.enso.table.excel.ExcelRange;
+import org.enso.table.excel.ExcelRow;
+import org.enso.table.excel.ExcelSheet;
+
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.util.Arrays;
+import java.util.function.Function;
+
+public class ExcelWriter {
+  private static final double SECONDS_IN_A_DAY = 86400.0;
+
+  private static Function<Object, Boolean> ensoToTextCallback;
+
+  public static Function<Object, Boolean> getEnsoToTextCallback() {
+    return ensoToTextCallback;
+  }
+
+  public static void getEnsoToTextCallback(Function<Object, Boolean> callback) {
+    ensoToTextCallback = callback;
+  }
+
+  public static void writeTableToSheet(Workbook workbook, int sheetIndex, boolean replace, int firstRow, Table table, Long rowLimit, ExcelHeaders.HeaderBehavior headers)
+      throws ExistingDataException, IllegalStateException {
+    if (sheetIndex == 0 || sheetIndex > workbook.getNumberOfSheets()) {
+      int i = 1;
+      while (workbook.getSheet("Sheet" + i) != null) {
+        i++;
+      }
+
+      Sheet sheet = workbook.createSheet("Sheet" + i);
+      if (sheetIndex == 0) {
+        workbook.setSheetOrder(sheet.getSheetName(), 0);
+      }
+
+      writeTableToSheet(workbook, sheet, firstRow, 1, table, rowLimit, headers != ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES);
+    } else if (replace) {
+      if (headers == ExcelHeaders.HeaderBehavior.INFER) {
+        ExcelSheet excelSheet = new ExcelSheet(workbook, sheetIndex);
+        headers = shouldWriteHeaders(excelSheet, firstRow + 1, 1, -1)
+            ? ExcelHeaders.HeaderBehavior.USE_FIRST_ROW_AS_HEADERS
+            : ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES;
+      }
+
+      String sheetName = workbook.getSheetName(sheetIndex - 1);
+      workbook.removeSheetAt(sheetIndex - 1);
+
+      Sheet sheet = workbook.createSheet(sheetName);
+      workbook.setSheetOrder(sheetName, sheetIndex - 1);
+      writeTableToSheet(workbook, sheet, firstRow, 1, table, rowLimit, headers != ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES);
+    } else {
+      throw new ExistingDataException("Sheet already exists, and cannot be replaced in current mode.");
+    }
+  }
+
+  public static void writeTableToSheet(Workbook workbook, String sheetName, boolean replace, int firstRow, Table table, Long rowLimit, ExcelHeaders.HeaderBehavior headers)
+      throws ExistingDataException, IllegalStateException {
+    int sheetIndex = workbook.getNumberOfSheets() == 0 ? -1 : workbook.getSheetIndex(sheetName);
+    if (sheetIndex == -1) {
+      writeTableToSheet(workbook, workbook.createSheet(sheetName), firstRow, 1, table, rowLimit, headers != ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES);
+    } else if (replace) {
+      if (headers == ExcelHeaders.HeaderBehavior.INFER) {
+        ExcelSheet excelSheet = new ExcelSheet(workbook, sheetIndex);
+        headers = shouldWriteHeaders(excelSheet, firstRow + 1, 1, -1)
+            ? ExcelHeaders.HeaderBehavior.USE_FIRST_ROW_AS_HEADERS
+            : ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES;
+      }
+
+      workbook.removeSheetAt(sheetIndex);
+      Sheet sheet = workbook.createSheet(sheetName);
+      workbook.setSheetOrder(sheetName, sheetIndex);
+      writeTableToSheet(workbook, sheet, firstRow, 1, table, rowLimit, headers != ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES);
+    } else {
+      throw new ExistingDataException("Sheet '" + sheetName + "' already exists, and cannot be replaced in current mode.");
+    }
+  }
+
+  public static void writeTableToRange(Workbook workbook, String rangeNameOrAddress, boolean replace, int skipRows, Table table, Long rowLimit, ExcelHeaders.HeaderBehavior headers)
+      throws InvalidLocationException, IllegalStateException, RangeExceededException, ExistingDataException {
+    Name name = workbook.getName(rangeNameOrAddress);
+    ExcelRange excelRange;
+    try {
+      excelRange = new ExcelRange(name == null ? rangeNameOrAddress : name.getRefersToFormula());
+    } catch (IllegalArgumentException e) {
+      throw new InvalidLocationException("Invalid range name or address '" + rangeNameOrAddress + "'.");
+    }
+    writeTableToRange(workbook, excelRange, replace, skipRows, table, rowLimit, headers);
+  }
+
+  public static void writeTableToRange(Workbook workbook, ExcelRange range, boolean replace, int skipRows, Table table, Long rowLimit, ExcelHeaders.HeaderBehavior headers)
+      throws InvalidLocationException, IllegalStateException, RangeExceededException, ExistingDataException {
+    int sheetIndex = workbook.getSheetIndex(range.getSheetName());
+    if (sheetIndex == -1) {
+      throw new InvalidLocationException("Unknown sheet '" + range.getSheetName() + "'.");
+    }
+    ExcelSheet sheet = new ExcelSheet(workbook, sheetIndex);
+
+    if (skipRows != 0) {
+      if (range.isWholeColumn()) {
+        range = new ExcelRange(range.getSheetName(), skipRows + 1, range.getLeftColumn(), workbook.getSpreadsheetVersion().getMaxRows(), range.getRightColumn());
+      } else if (range.isSingleCell()) {
+        range = new ExcelRange(range.getSheetName(), range.getTopRow() + skipRows, range.getLeftColumn());
+      } else {
+        range = new ExcelRange(range.getSheetName(), range.getTopRow() + skipRows, range.getLeftColumn(), range.getBottomRow(), range.getRightColumn());
+      }
+    }
+
+    if (range.isSingleCell()) {
+      ExcelRange expanded = ExcelRange.expandSingleCell(range, sheet);
+
+      if (headers == ExcelHeaders.HeaderBehavior.INFER) {
+        headers = shouldWriteHeaders(sheet, expanded.getTopRow(), expanded.getLeftColumn(), expanded.getRightColumn())
+            ? ExcelHeaders.HeaderBehavior.USE_FIRST_ROW_AS_HEADERS
+            : ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES;
+      }
+
+      // Expand to cover required size
+      int rowCount = (headers == ExcelHeaders.HeaderBehavior.USE_FIRST_ROW_AS_HEADERS ? 1 : 0) + table.rowCount();
+      if (expanded.getColumnCount() < table.getColumns().length || expanded.getRowCount() < rowCount) {
+        expanded = new ExcelRange(
+            expanded.getSheetName(),
+            expanded.getLeftColumn(),
+            expanded.getTopRow(),
+            Math.max(expanded.getRightColumn(), expanded.getLeftColumn() + table.getColumns().length - 1),
+            Math.max(expanded.getBottomRow(), expanded.getTopRow() + rowCount - 1));
+      }
+
+      checkExistingRange(workbook, expanded, replace, sheet);
+    } else {
+      // Check Size of Range
+      int rowCount = Math.min(Math.min(workbook.getSpreadsheetVersion().getMaxRows() - range.getTopRow() + 1, rowLimit == null ? Integer.MAX_VALUE : rowLimit.intValue()), table.rowCount());
+      if (range.getColumnCount() < table.getColumns().length || range.getRowCount() < rowCount) {
+        throw new RangeExceededException("Range is too small to fit all columns.");
+      }
+
+      if (headers == ExcelHeaders.HeaderBehavior.INFER) {
+        headers = shouldWriteHeaders(sheet, range.getTopRow(), range.getLeftColumn(), range.isWholeRow() ? -1 : range.getRightColumn())
+            ? ExcelHeaders.HeaderBehavior.USE_FIRST_ROW_AS_HEADERS
+            : ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES;
+      }
+
+      checkExistingRange(workbook, range, replace, sheet);
+    }
+
+    writeTableToSheet(workbook, sheet.getSheet(), range.getTopRow() - 1, range.getLeftColumn(), table, rowLimit, headers != ExcelHeaders.HeaderBehavior.EXCEL_COLUMN_NAMES);
+  }
+
+  private static void checkExistingRange(Workbook workbook, ExcelRange range, boolean replace, ExcelSheet sheet) throws ExistingDataException {
+    int topRow = range.isWholeColumn() ? 1 : range.getTopRow();
+    int bottomRow = range.isWholeColumn() ? workbook.getSpreadsheetVersion().getMaxRows() : range.getBottomRow();
+    int leftColumn = range.isWholeRow() ? 1 : range.getLeftColumn();
+    int rightColumn = range.isWholeRow() ? workbook.getSpreadsheetVersion().getMaxColumns() : range.getRightColumn();
+
+    for (int row = topRow; row <= bottomRow; row++) {
+      ExcelRow excelRow = sheet.get(row);
+      if (excelRow != null) {
+        for (int column = leftColumn; column <= rightColumn; column++) {
+          Cell cell = excelRow.get(column);
+          if (cell != null) {
+            if (replace) {
+              cell.setBlank();
+            } else {
+              throw new ExistingDataException("Range is not empty, and cannot be replaced in current mode.");
+            }
+          }
+        }
+      }
+    }
+  }
+
+  /**
+   * Creates an empty workbook.
+   * @param xls_format specifies whether the file is in Excel Binary Format (95-2003 format).
+   * @return a {@link Workbook} containing the specified data.
+   */
+  public static Workbook createWorkbook(boolean xls_format) {
+    return xls_format ? new HSSFWorkbook() : new XSSFWorkbook();
+  }
+
+  private static void writeTableToSheet(Workbook workbook, Sheet sheet, int firstRow, int firstColumn, Table table, Long rowLimit, boolean headers)
+    throws IllegalStateException {
+    int rowCount = Math.min(Math.min(workbook.getSpreadsheetVersion().getMaxRows() - firstRow, rowLimit == null ? Integer.MAX_VALUE : rowLimit.intValue()), table.rowCount());
+    int currentRow = firstRow;
+    Column[] columns = table.getColumns();
+
+    if (headers) {
+      Row row = sheet.createRow(currentRow);
+      for (int i = 0; i < columns.length; i++) {
+        row.createCell(i + firstColumn - 1, CellType.STRING).setCellValue(columns[i].getName());
+      }
+      currentRow++;
+    }
+
+    if (rowCount == 0) {
+      return;
+    }
+
+    Storage[] storages = Arrays.stream(columns).map(Column::getStorage).toArray(Storage[]::new);
+    for (int i = 0; i < rowCount; i++) {
+      Row row = sheet.getRow(currentRow);
+      if (row == null) {
+        row = sheet.createRow(currentRow);
+      }
+
+      for (int j = 0; j < columns.length; j++) {
+        Storage storage = storages[j];
+        int idx = j + firstColumn - 1;
+
+        Cell cell = row.getCell(idx);
+        if (cell == null) {
+          cell = row.createCell(idx);
+        }
+
+        writeValueToCell(cell, i, storage, workbook);
+      }
+      currentRow++;
+    }
+
+    workbook.setForceFormulaRecalculation(true);
+  }
+
+  private static CellStyle getDateTimeStyle(Workbook workbook, String format) {
+    for(int i = 0; i < workbook.getNumCellStyles(); i++) {
+      CellStyle style = workbook.getCellStyleAt(i);
+      if (style.getDataFormatString().equals(format)) {
+        return style;
+      }
+    }
+
+    CellStyle newStyle = workbook.createCellStyle();
+    newStyle.setDataFormat(workbook.createDataFormat().getFormat(format));
+    return newStyle;
+  }
+
+  private static void writeValueToCell(Cell cell, int j, Storage storage, Workbook workbook)
+    throws IllegalStateException {
+    if (storage.isNa(j)) {
+      cell.setBlank();
+    } else if (storage instanceof DoubleStorage doubleStorage) {
+      cell.setCellValue(doubleStorage.getItem(j));
+    } else if (storage instanceof LongStorage longStorage) {
+      cell.setCellValue(longStorage.getItem(j));
+    } else if (storage instanceof BoolStorage boolStorage) {
+      cell.setCellValue(boolStorage.getItem(j));
+    } else {
+      Object value = storage.getItemBoxed(j);
+      switch (value) {
+        case String s -> cell.setCellValue(s);
+        case Boolean b -> cell.setCellValue(b);
+        case Double d -> cell.setCellValue(d);
+        case Long l -> cell.setCellValue(l);
+        case LocalDateTime ldt -> {
+          cell.setCellValue(ldt);
+          cell.setCellStyle(getDateTimeStyle(workbook, "yyyy-MM-dd HH:mm:ss"));
+        }
+        case LocalDate ld -> {
+          cell.setCellValue(ld);
+          cell.setCellStyle(getDateTimeStyle(workbook, "yyyy-MM-dd"));
+        }
+        case LocalTime lt -> {
+          cell.setCellValue(lt.toSecondOfDay() / SECONDS_IN_A_DAY);
+          cell.setCellStyle(getDateTimeStyle(workbook, "HH:mm:ss"));
+        }
+        default -> {
+          if (ensoToTextCallback != null) {
+            cell.setCellValue(ensoToTextCallback.apply(value));
+          } else {
+            throw new IllegalStateException("Enso to text callback is not set. Unable to process value.");
+          }
+        }
+      }
+    }
+  }
+
+  /**
+   * Determines if headers should be written for the given range in {@code INFER} mode.
+   *
+   * Unlike in the {@code ExcelReader}, if empty this will default to True.
+   * @param excelSheet the Excel sheet to check.
+   * @param topRow top row index (1-based) of the range to check.
+   * @param startCol start column index (1-based) of the range to check.
+   * @param endCol end column index (1-based) of the range to check. If -1 will continue until end of row.
+   * @return true if the range has headers.
+   */
+  private static boolean shouldWriteHeaders(ExcelSheet excelSheet, int topRow, int startCol, int endCol) {
+    ExcelRow row = excelSheet.get(topRow);
+
+    // If the first row is missing or empty, return true as defaults to writing headers.
+    if (row == null || row.isEmpty(startCol, endCol)) {
+      return true;
+    }
+
+    // If the first row is not empty, check if all text.
+    if (row.getCellsAsText(startCol, endCol) == null) {
+      return false;
+    }
+
+    // If the second row is missing or empty or contains text, return false.
+    ExcelRow nextRow = excelSheet.get(topRow + 1);
+    return (nextRow != null && nextRow.getCellsAsText(startCol, endCol) == null);
+  }
+}

test/Table_Tests/src/Excel_Spec.enso

@@ -1,17 +1,23 @@
 from Standard.Base import Nothing, File, Illegal_Argument_Error, True, False
-
+import Standard.Base.System.File.Existing_File_Behavior
+from Standard.Base.System.File import File_Already_Exists_Error
 import Standard.Base.Data.Time.Date
 
 import Standard.Table.Io.File_Read
 import Standard.Table.Io.File_Format
+import Standard.Table.Data.Column_Mapping
+from Standard.Table.Data.Column_Selector as Column_Selector_Module import By_Index
 from Standard.Table.Io.Excel import Excel_Range, Sheet_Names, Range_Names, Sheet, Cell_Range
-from Standard.Table.Error as Table_Errors import Invalid_Output_Column_Names, Duplicate_Output_Column_Names
+from Standard.Table.Error as Table_Errors import Invalid_Output_Column_Names, Duplicate_Output_Column_Names, Invalid_Location, Range_Exceeded, Existing_Data
+from Standard.Table.Data.Data_Formatter as Data_Formatter_Module import Data_Formatter
 
 import Standard.Test
 import Standard.Test.Problems
 
 import Standard.Examples
 
+import project.Util
+
 spec_fmt header file read_method =
     Test.group header <|
         Test.specify "should read the specified sheet by index and use correct headers" <|
@@ -61,6 +67,96 @@ spec_fmt header file read_method =
             t_3.at 'B' . to_vector . should_equal [Nothing, 30]
             t_3.at 'C' . to_vector . should_equal [43.2, 54]
 
+spec_write suffix test_sheet_name =
+    Test.group ("Write " + suffix + " Files") <|
+        ## We disable parsing dates, because date support is not advanced enough
+           for these tests. This should ideally be re-enabled with the
+           completion of the following story:
+           https://www.pivotaltracker.com/story/show/181755990
+        no_dates = File_Format.Delimited "," value_formatter=(Data_Formatter date_formats=[] time_formats=[] datetime_formats=[])
+        out = Enso_Project.data / ('out.' + suffix)
+        table = Enso_Project.data/'varied_column.csv' . read (format = no_dates)
+        clothes = Enso_Project.data/'clothes.csv' . read (format = no_dates)
+        sub_clothes = clothes.select_columns (By_Index [0, 1])
+
+        Test.specify 'should write a table to non-existent file as a new sheet with headers' <|
+            out.delete_if_exists
+            table.write out
+            written = out.read
+            written.should_equal table
+            out.delete_if_exists
+
+        Test.specify 'should create new sheets at the start if index is 0' <|
+            out.delete_if_exists
+            table.write out (File_Format.Excel (Sheet 0))
+            clothes.write out (File_Format.Excel (Sheet 0))
+            read_1 = out.read (File_Format.Excel (Sheet "Sheet1"))
+            read_1 . should_equal table
+            read_2 = out.read (File_Format.Excel (Sheet "Sheet2"))
+            read_2 . should_equal clothes
+            read_3 = out.read (File_Format.Excel (Sheet_Names))
+            read_3 . should_equal ["Sheet2", "Sheet1"]
+            out.delete_if_exists
+
+        Test.specify 'should write a table to specific single cell location of an existing sheet' <|
+            out.delete_if_exists
+            (Enso_Project.data / test_sheet_name) . copy_to out
+            table.write out (File_Format.Excel (Cell_Range "Another!G1"))
+            written = out.read (File_Format.Excel (Cell_Range "Another!G1"))
+            written.should_equal table
+            out.delete_if_exists
+
+        Test.specify 'should clear out an existing fixed range and replace' <|
+            out.delete_if_exists
+            (Enso_Project.data / test_sheet_name) . copy_to out
+            sub_clothes.write out (File_Format.Excel (Cell_Range "Another!A1:D20"))
+            written = out.read (File_Format.Excel (Cell_Range "Another!A1"))
+            written.should_equal sub_clothes
+            out.delete_if_exists
+
+        Test.specify 'should clear out an existing range and replace' <|
+            out.delete_if_exists
+            (Enso_Project.data / test_sheet_name) . copy_to out
+            sub_clothes.write out (File_Format.Excel (Cell_Range "Another!A1"))
+            written = out.read (File_Format.Excel (Cell_Range "Another!A1"))
+            written.should_equal sub_clothes
+            out.delete_if_exists
+
+        Test.specify 'should result in Invalid_Location error if trying to write in a bad location' <|
+            out.delete_if_exists
+            (Enso_Project.data / test_sheet_name) . copy_to out
+            sub_clothes.write out (File_Format.Excel (Cell_Range "DoesNotExist!A1")) . should_fail_with Invalid_Location
+            sub_clothes.write out (File_Format.Excel (Cell_Range "DoesNotExist!A1:B2")) . should_fail_with Invalid_Location
+            sub_clothes.write out (File_Format.Excel (Cell_Range "SillyRangeName")) . should_fail_with Invalid_Location
+            out.delete_if_exists
+
+        Test.specify 'should result in Range_Exceeded error if trying to write in too small a range' <|
+            out.delete_if_exists
+            (Enso_Project.data / test_sheet_name) . copy_to out
+            sub_clothes.write out (File_Format.Excel (Cell_Range "Another!A1:B2")) . should_fail_with Range_Exceeded
+            out.delete_if_exists
+
+        Test.specify 'should result in Existing_Data error if in Error mode and trying to replace' <|
+            out.delete_if_exists
+            (Enso_Project.data / test_sheet_name) . copy_to out
+            sub_clothes.write out (File_Format.Excel (Sheet 1)) on_existing_file=Existing_File_Behavior.Error . should_fail_with Existing_Data
+            sub_clothes.write out (File_Format.Excel (Sheet "Another")) on_existing_file=Existing_File_Behavior.Error . should_fail_with Existing_Data
+            sub_clothes.write out (File_Format.Excel (Cell_Range "Another!A1")) on_existing_file=Existing_File_Behavior.Error . should_fail_with Existing_Data
+            sub_clothes.write out (File_Format.Excel (Cell_Range "Sheet1!A9")) on_existing_file=Existing_File_Behavior.Error . should_fail_with Existing_Data
+            out.delete_if_exists
+
+        Test.specify 'should not allow adding a new sheet if in Error mode and not clashing' <|
+            out.delete_if_exists
+            (Enso_Project.data / test_sheet_name) . copy_to out
+            sub_clothes.write out (File_Format.Excel (Sheet "Testing")) on_existing_file=Existing_File_Behavior.Error . should_fail_with File_Already_Exists_Error
+
+        Test.specify 'should write a table to non-existent file as a new sheet without headers' <|
+            out.delete_if_exists
+            table.write out (File_Format.Excel (Sheet "Sheet1") headers=False)
+            written = out.read
+            written.should_equal (table.rename_columns (Column_Mapping.By_Position ['A', 'B', 'C', 'D', 'E', 'F']))
+            out.delete_if_exists
+
 spec =
     Test.group 'Excel Range' <|
         check_range excel_range sheet_name tlbr_vector single_cell=False =
@@ -321,4 +417,8 @@ spec =
             problems = [Duplicate_Output_Column_Names ["DD"]]
             Problems.test_problem_handling action problems tester
 
+    here.spec_write "xlsx" 'TestSheet.xlsx'
+    here.spec_write "xls" 'TestSheetOld.xls'
+
+
 main = Test.Suite.run_main here.spec

test/Table_Tests/src/In_Memory_Tests.enso

@@ -10,7 +10,6 @@ import project.Delimited_Write_Spec
 import project.Excel_Spec
 import project.Json_Spec
 import project.Table_Spec
-import project.Spreadsheet_Spec
 import project.Aggregate_Column_Spec
 import project.Aggregate_Spec
 
@@ -21,7 +20,6 @@ in_memory_spec =
     Delimited_Write_Spec.spec
     Excel_Spec.spec
     Json_Spec.spec
-    Spreadsheet_Spec.spec
     Table_Spec.spec
     Model_Spec.spec
     Aggregate_Column_Spec.spec

test/Table_Tests/src/Spreadsheet_Spec.enso

@@ -1,68 +0,0 @@
-from Standard.Base import all
-import Standard.Test
-import Standard.Table
-import Standard.Table.Io.File_Format
-import Standard.Table.Io.File_Read
-from Standard.Table.Io.Excel import Sheet
-from Standard.Table.Data.Data_Formatter as Data_Formatter_Module import Data_Formatter
-
-import project.Util
-
-
-spec =
-
-    Test.group 'XLSX writing' <|
-        ## We disable parsing dates, because date support is not advanced enough
-           for these tests. This should ideally be re-enabled with the
-           completion of the following story:
-           https://www.pivotaltracker.com/story/show/181755990
-        no_dates = File_Format.Delimited "," value_formatter=(Data_Formatter date_formats=[] time_formats=[] datetime_formats=[])
-        out = Enso_Project.data / 'out.xlsx'
-        table = Enso_Project.data/'varied_column.csv' . read (format = no_dates)
-        clothes = Enso_Project.data/'clothes.csv' . read (format = no_dates)
-
-        Test.specify 'should write tables to non-existent XLSX files' <|
-            out.delete_if_exists
-            table.write_xlsx out
-            written = out.read
-            written.should_equal table
-            out.delete_if_exists
-
-        Test.specify 'should create a new sheet if it already exists and write mode is Create' <|
-            out.delete_if_exists
-            table.write_xlsx out sheet='Foo'
-            clothes.write_xlsx out sheet='Foo'
-            read_1 = out.read (File_Format.Excel (Sheet "Foo"))
-            read_1 . should_equal table
-            read_2 = out.read (File_Format.Excel (Sheet "Foo 1"))
-            read_2 . should_equal clothes
-            out.delete_if_exists
-
-        Test.specify 'should overwrite a sheet if it already exists and write mode is Overwrite' <|
-            out.delete_if_exists
-            table.write_xlsx out sheet='Foo'
-            clothes.write_xlsx out sheet='Foo' write_mode=Table.Spreadsheet_Write_Mode.Overwrite
-            read = out.read (File_Format.Excel (Sheet "Foo"))
-            read . should_equal clothes
-            out.delete_if_exists
-
-        Test.specify 'should append to a sheet if it already exists and write mode is Append' <|
-            out.delete_if_exists
-            clothes.write_xlsx out sheet='Foo'
-            clothes.write_xlsx out sheet='Foo' write_mode=Table.Spreadsheet_Write_Mode.Append include_header=False
-            read = out.read (File_Format.Excel (Sheet "Foo"))
-            read . should_equal (clothes.concat clothes)
-            out.delete_if_exists
-
-        Test.specify 'should write multiple files if row limit is specified' <|
-            out_1 = Enso_Project.data / 'out_1.xlsx'
-            out_2 = Enso_Project.data / 'out_2.xlsx'
-            out_1.delete_if_exists
-            out_2.delete_if_exists
-            clothes.write_xlsx out max_rows_per_file=4
-            out_1.read . should_equal (clothes.take_start 4)
-            out_2.read . should_equal (clothes.take_end 2)
-            out_1.delete_if_exists
-            out_2.delete_if_exists
-
-main = Test.Suite.run_main here.spec