split padding out from truncation

This makes these functions a bit more composable!

Heads up @jankatins; this is a breaking change (for the better!)

refs: https://github.com/wez/wezterm/issues/647

config/src/lua.rs

@@ -122,9 +122,34 @@ pub fn make_lua_context(config_file: &Path) -> anyhow::Result<Lua> {
         )?;
 
         wezterm_mod.set(
-            "truncate_to_width",
-            lua.create_function(
-                |_, (s, max_width, min_width): (String, usize, Option<usize>)| {
+            "pad_right",
+            lua.create_function(|_, (mut result, width): (String, usize)| {
+                let mut len = unicode_column_width(&result);
+                while len < width {
+                    result.push(' ');
+                    len += 1;
+                }
+
+                Ok(result)
+            })?,
+        )?;
+
+        wezterm_mod.set(
+            "pad_left",
+            lua.create_function(|_, (mut result, width): (String, usize)| {
+                let mut len = unicode_column_width(&result);
+                while len < width {
+                    result.insert(0, ' ');
+                    len += 1;
+                }
+
+                Ok(result)
+            })?,
+        )?;
+
+        wezterm_mod.set(
+            "truncate_right",
+            lua.create_function(|_, (s, max_width): (String, usize)| {
                 let mut result = String::new();
                 let mut len = 0;
                 for g in s.graphemes(true) {
@@ -136,25 +161,13 @@ pub fn make_lua_context(config_file: &Path) -> anyhow::Result<Lua> {
                     len += g_len;
                 }
 
-                    if let Some(min_width) = min_width {
-                        while len < min_width {
-                            if len >= max_width {
-                                break;
-                            }
-                            result.push(' ');
-                            len += 1;
-                        }
-                    }
-
                 Ok(result)
-                },
-            )?,
+            })?,
         )?;
 
         wezterm_mod.set(
-            "truncate_left_to_width",
-            lua.create_function(
-                |_, (s, max_width, min_width): (String, usize, Option<usize>)| {
+            "truncate_left",
+            lua.create_function(|_, (s, max_width): (String, usize)| {
                 let mut result = vec![];
                 let mut len = 0;
                 for g in s.graphemes(true).rev() {
@@ -166,20 +179,9 @@ pub fn make_lua_context(config_file: &Path) -> anyhow::Result<Lua> {
                     len += g_len;
                 }
 
-                    if let Some(min_width) = min_width {
-                        while len < min_width {
-                            if len >= max_width {
-                                break;
-                            }
-                            result.push(" ");
-                            len += 1;
-                        }
-                    }
-
                 result.reverse();
                 Ok(result.join(""))
-                },
-            )?,
+            })?,
         )?;
 
         wezterm_mod.set("font", lua.create_function(font)?)?;

docs/changelog.md

@@ -46,7 +46,7 @@ As features stabilize some brief notes about them will accumulate here.
 * Fixed: tabs would remain hovered after moving the mouse down into the main terminal area [#591](https://github.com/wez/wezterm/issues/591)
 * New: [tab_bar_at_bottom](config/lua/config/tab_bar_at_bottom.md) setting to put the tab bar at the bottom of the window [#278](https://github.com/wez/wezterm/issues/278)
 * New: [wezterm.column_width](config/lua/wezterm/column_width.md) function for measuring the displayed width of a string
-* New: [wezterm.truncate_to_width](config/lua/wezterm/truncate_to_width.md) and [wezterm.truncate_left_to_width](config/lua/wezterm/truncate_left_to_width.md) function for truncating/padding a string based on its displayed width
+* New: [wezterm.pad_left](config/lua/wezterm/pad_left.md), [wwezterm.pad_right](config/lua/wezterm/pad_right.md), [wezterm.truncate_left](config/lua/wezterm/truncate_left.md) and [wezterm.truncate_right](config/lua/wezterm/truncate_right.md) function for truncating/padding a string based on its displayed width
 * Updated bundled `Noto Color Emoji` font to version 2.020 with unicode 13.1 support. Thanks to [@4cm4k1](https://github.com/4cm4k1)! [#742](https://github.com/wez/wezterm/pull/742)
 * Fixed: Numpad Enter reported as CTRL-C on macOS [#739](https://github.com/wez/wezterm/issues/739)
 * Fixed: mouse reporting gbutton state not cleared when focus is lost, eg: from clicking a link [#744](https://github.com/wez/wezterm/issues/744)

docs/config/lua/wezterm/pad_left.md

@@ -0,0 +1,15 @@
+# wezterm.pad_left(string, min_width)
+
+*Since: nightly builds only*
+
+Returns a copy of `string` that is at leasst `min_width` columns
+(as measured by [wezterm.column_width](column_width.md)).
+
+If the string is shorter than `min_width`, spaces are added to
+the left end of the string.
+
+For example, `wezterm.pad_left("o", 3)` returns `"  o"`.
+
+See also: [wezterm.truncate_left](truncate_left.md), [wezterm.pad_right](pad_right.md).
+
+

docs/config/lua/wezterm/pad_right.md

@@ -0,0 +1,16 @@
+# wezterm.pad_right(string, min_width)
+
+*Since: nightly builds only*
+
+Returns a copy of `string` that is at leasst `min_width` columns
+(as measured by [wezterm.column_width](column_width.md)).
+
+If the string is shorter than `min_width`, spaces are added to
+the right end of the string.
+
+For example, `wezterm.pad_righ("o", 3)` returns `"o  "`.
+
+See also: [wezterm.truncate_left](truncate_left.md), [wezterm.pad_left](pad_left.md).
+
+
+

docs/config/lua/wezterm/truncate_left.md

@@ -0,0 +1,14 @@
+# wezterm.truncate_left(string, max_width)
+
+*Since: nightly builds only*
+
+Returns a copy of `string` that is no longer than `max_width` columns
+(as measured by [wezterm.column_width](column_width.md)).
+
+Truncation occurs by removing excess characters from the left
+end of the string.
+
+For example, `wezterm.truncate_left("hello", 3)` returns `"llo"`.
+
+See also: [wezterm.truncate_right](truncate_right.md), [wezterm.pad_right](pad_right.md).
+

docs/config/lua/wezterm/truncate_left_to_width.md

@@ -1,15 +0,0 @@
-# wezterm.truncate_left_to_width(string, max_width, min_width)
-
-*Since: nightly builds only*
-
-Returns a copy of `string` that is no longer than `max_width` columns
-(as measured by [wezterm.column_width](column_width.md)), and, optionally,
-no shorter than `min_width` columns, padding out with spaces.
-
-Truncation and padding occur on the left hand side of the string.
-
-For example, `wezterm.truncate_to_width("hello", 3)` returns `"llo"`,
-and `wezterm.truncate_to_width("a", 10, 5)` returns "    a"`.
-
-See also: [wezterm.truncate_to_width](truncate_to_width.md)
-

docs/config/lua/wezterm/truncate_right.md

@@ -0,0 +1,13 @@
+# wezterm.truncate_right(string, max_width)
+
+*Since: nightly builds only*
+
+Returns a copy of `string` that is no longer than `max_width` columns
+(as measured by [wezterm.column_width](column_width.md)).
+
+Truncation occurs by reemoving excess characters from the right end
+of the string.
+
+For example, `wezterm.truncate_right("hello", 3)` returns `"hel"`,
+
+See also: [wezterm.truncate_left](truncate_left.md), [wezterm.pad_left](pad_left.md).

docs/config/lua/wezterm/truncate_to_width.md

@@ -1,14 +0,0 @@
-# wezterm.truncate_to_width(string, max_width, min_width)
-
-*Since: nightly builds only*
-
-Returns a copy of `string` that is no longer than `max_width` columns
-(as measured by [wezterm.column_width](column_width.md)), and, optionally,
-no shorter than `min_width` columns, padding out with spaces.
-
-Truncation and padding occur on the right hand side of the string.
-
-For example, `wezterm.truncate_to_width("hello", 3)` returns `"hel"`,
-and `wezterm.truncate_to_width("a", 10, 5)` returns "a    "`.
-
-See also: [wezterm.truncate_left_to_width](truncate_left_to_width.md)