Implement Table from Text conversion (#3478)

Implements https://www.pivotaltracker.com/story/show/181824168

CHANGELOG.md

@@ -128,6 +128,8 @@
 - [Integrated value parsing with the `Delimited` file reader.][3463]
 - [Implemented the `Infer` setting for headers in the `Delimited` file format
   and made it the default.][3472]
+- [Implemented a `Table.from Text` conversion allowing to parse strings
+  representing `Delimited` files without storing them on the filesystem.][3478]
 
 [debug-shortcuts]:
   https://github.com/enso-org/enso/blob/develop/app/gui/docs/product/shortcuts.md#debug
@@ -199,6 +201,7 @@
 [3462]: https://github.com/enso-org/enso/pull/3462
 [3463]: https://github.com/enso-org/enso/pull/3463
 [3472]: https://github.com/enso-org/enso/pull/3472
+[3478]: https://github.com/enso-org/enso/pull/3478
 
 #### Enso Compiler
 

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

@@ -7,9 +7,11 @@ 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.Format
+import Standard.Table.Io.File_Format
 import Standard.Table.Internal.Table_Helpers
 import Standard.Table.Internal.Aggregate_Column_Helper
 import Standard.Table.Internal.Parse_Values_Helper
+import Standard.Table.Internal.Delimited_Reader
 
 from Standard.Table.Data.Order_Rule as Order_Rule_Module import Order_Rule
 from Standard.Table.Data.Column_Selector as Column_Selector_Module import Column_Selector, By_Index
@@ -28,6 +30,7 @@ polyglot java import org.enso.table.data.table.Column as Java_Column
 polyglot java import org.enso.table.operations.OrderBuilder
 polyglot java import org.enso.table.format.csv.Writer as Csv_Writer
 polyglot java import org.enso.table.format.xlsx.Writer as Spreadsheet_Writer
+polyglot java import java.io.StringReader
 
 ## Creates a new table from a vector of `[name, items]` pairs.
 
@@ -1523,3 +1526,7 @@ print_table header rows indices_count format_term =
    - y: The right operand to the comparator.
 comparator_to_java : (Any -> Any -> Ordering) -> Any -> Any -> Integer
 comparator_to_java cmp x y = cmp x y . to_sign
+
+Table.from (that : Text) (format:File_Format.Delimited|File_Format.Fixed_Width = File_Format.Delimited '\t') (on_problems:Problem_Behavior=Report_Warning) =
+    java_reader = StringReader.new that
+    Delimited_Reader.read_from_reader format java_reader on_problems

distribution/lib/Standard/Table/0.0.0-dev/src/Internal/Delimited_Reader.enso

@@ -18,6 +18,7 @@ polyglot java import java.io.IOException
 polyglot java import com.univocity.parsers.common.TextParsingException
 polyglot java import org.enso.base.Encoding_Utils
 polyglot java import java.io.InputStream
+polyglot java import java.io.Reader
 
 polyglot java import org.enso.table.parsing.IdentityParser
 polyglot java import org.enso.table.parsing.TypeInferringParser
@@ -45,9 +46,6 @@ read_file format file on_problems =
 ## PRIVATE
    Reads an input stream according to the provided format.
 
-   The `encoding` parameter is ignored, instead the provided stream should
-   handle any necessary decoding.
-
    Arguments:
    - format: The specification of the delimited file format.
    - java_stream: A Java `InputStream` used as the data source.
@@ -60,8 +58,36 @@ read_file format file on_problems =
      integer.
    - related_file: The file related to the provided `java_stream`, if available,
      or `Nothing`. It is used for more detailed error reporting.
-read_stream : Delimited -> InputStream -> Problem_Behavior -> File | Nothing -> Any
+read_stream : Delimited -> InputStream -> Problem_Behavior -> Integer -> File | Nothing -> Any
 read_stream format java_stream on_problems max_columns=4096 related_file=Nothing =
+    handle_io_exception ~action = Panic.catch IOException action caught_panic->
+        Error.throw (File.wrap_io_exception related_file caught_panic.payload.cause)
+
+    java_charset = format.encoding.to_java_charset
+    handle_io_exception <|
+        Encoding_Utils.with_stream_decoder java_stream java_charset reporting_stream_decoder->
+            result = here.read_from_reader format reporting_stream_decoder on_problems max_columns
+            decoding_problems = Vector.Vector reporting_stream_decoder.getReportedProblems . map Encoding_Error
+            on_problems.attach_problems_after result decoding_problems
+
+## PRIVATE
+   Reads data from the provided `Reader` according to the provided format.
+
+   The `encoding` parameter is ignored, instead the provided reader should
+   handle any necessary decoding.
+
+   Arguments:
+   - format: The specification of the delimited file format.
+   - java_reader: A Java `Reader` used as the source of decoded characters.
+   - on_problems: Specifies the behavior when a problem occurs during the
+     operation. By default, a warning is issued, but the operation proceeds.
+     If set to `Report_Error`, the operation fails with a dataflow error.
+     If set to `Ignore`, the operation proceeds without errors or warnings.
+   - max_columns: Specifies the limit of columns to read. The limit is set to
+     avoid `OutOfMemory` errors on malformed files. It must be a positive
+     integer.
+read_from_reader : Delimited -> InputStream -> Problem_Behavior -> Integer -> Any
+read_from_reader format java_reader on_problems max_columns=4096 =
     java_headers = case format.headers of
         True -> DelimitedReader.HeaderBehavior.USE_FIRST_ROW_AS_HEADERS
         Infer -> DelimitedReader.HeaderBehavior.INFER
@@ -91,25 +117,21 @@ read_stream format java_stream on_problems max_columns=4096 related_file=Nothing
 
     translate_parsing_exception caught_panic =
         cause = caught_panic.payload.cause.getCause
-        if Java.is_instance cause IOException then File.wrap_io_exception related_file cause else
+        if Java.is_instance cause IOException then Panic.throw cause else
             Error.throw (Parser_Error caught_panic.payload)
     handle_parsing_exception = Panic.catch TextParsingException handler=translate_parsing_exception
 
-    java_charset = format.encoding.to_java_charset
     handle_illegal_arguments <| handle_parsing_failure <| handle_parsing_exception <|
-        Encoding_Utils.with_stream_decoder java_stream java_charset reporting_stream_decoder->
-            warnings_as_errors = on_problems == Problem_Behavior_Module.Report_Error
-            base_parser = if format.quote.is_nothing then IdentityParser.new else
-                QuoteStrippingParser.new format.quote
-            value_parser = if format.value_formatter.is_nothing then base_parser else
-                wrapped = format.value_formatter.wrap_base_parser base_parser
-                TypeInferringParser.new format.value_formatter.get_specific_type_parsers.to_array wrapped
-            cell_type_guesser = if format.headers != Infer then Nothing else
-                formatter = format.value_formatter.if_nothing Data_Formatter
-                TypeInferringParser.new formatter.get_specific_type_parsers.to_array IdentityParser.new
-            reader = DelimitedReader.new reporting_stream_decoder format.delimiter format.quote format.quote_escape java_headers skip_rows row_limit max_columns value_parser cell_type_guesser format.keep_invalid_rows warnings_as_errors
-            result = Table.Table reader.read
-            decoding_problems = Vector.Vector reporting_stream_decoder.getReportedProblems . map Encoding_Error
-            parsing_problems = Vector.Vector reader.getReportedProblems . map translate_parsing_problem
-            problems = decoding_problems + parsing_problems
-            on_problems.attach_problems_after result problems
+        warnings_as_errors = on_problems == Problem_Behavior_Module.Report_Error
+        base_parser = if format.quote.is_nothing then IdentityParser.new else
+            QuoteStrippingParser.new format.quote
+        value_parser = if format.value_formatter.is_nothing then base_parser else
+            wrapped = format.value_formatter.wrap_base_parser base_parser
+            TypeInferringParser.new format.value_formatter.get_specific_type_parsers.to_array wrapped
+        cell_type_guesser = if format.headers != Infer then Nothing else
+            formatter = format.value_formatter.if_nothing Data_Formatter
+            TypeInferringParser.new formatter.get_specific_type_parsers.to_array IdentityParser.new
+        reader = DelimitedReader.new java_reader format.delimiter format.quote format.quote_escape java_headers skip_rows row_limit max_columns value_parser cell_type_guesser format.keep_invalid_rows warnings_as_errors
+        result = Table.Table reader.read
+        parsing_problems = Vector.Vector reader.getReportedProblems . map translate_parsing_problem
+        on_problems.attach_problems_after result parsing_problems

test/Table_Tests/src/Delimited_Read_Spec.enso

@@ -311,4 +311,21 @@ spec =
             t2.at "c" . to_vector . should_equal [3, 6]
             t2.columns.map .name . should_equal ["a", "b", "c"]
 
+        Test.specify "should be able to parse raw text" <|
+            text1 = """
+                a,b,c
+                1,2,3
+                4,5,6
+            t1 = Table.Table.from text1 (format = File_Format.Delimited ",")
+            t1.columns.map .name . should_equal ["a", "b", "c"]
+            t1.at "a" . to_vector . should_equal [1, 4]
+            t1.at "b" . to_vector . should_equal [2, 5]
+            t1.at "c" . to_vector . should_equal [3, 6]
+
+            text2 = 'a\tb\n1\t2\n3\t4'
+            t2 = Table.Table.from text2
+            t2.columns.map .name . should_equal ["a", "b"]
+            t2.at "a" . to_vector . should_equal [1, 3]
+            t2.at "b" . to_vector . should_equal [2, 4]
+
 main = Test.Suite.run_main here.spec