add doc.zero_width_string function

* add doc.zero_width_string function

* add doc.zero_width_string example test

* update changelog

Author: marcobacis

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Remove the `doc.to_string_builder` method.
+- The `doc` module gains the `zero_width_string` function
 
 ## v1.3.0 - 2023-01-03
 

src/glam/doc.gleam

@@ -236,6 +236,29 @@ pub fn from_string(string: String) -> Document {
   Text(string, string.length(string))
 }
 
+/// Turns a string into a document, without impacting in the line length in which
+/// the string is used.
+///
+/// This kind of string can be used to render non-visible characters
+/// e.g. ansi color codes
+///
+/// ## Examples
+///
+/// ```gleam
+/// // Should break in two lines, but doesn't because of the zero_width_string
+/// [
+///   zero_width_string("\u{001b}[1;31m"),
+///   from_string("I'm a red"),
+///   break(", ", ","),
+///   from_string("bold text"),
+/// ] |> concat |> group |> to_string(20)
+/// // -> "\u{001b}[1;31mI'm a red, bold text"
+/// ```
+///
+pub fn zero_width_string(string: String) -> Document {
+  Text(string, 0)
+}
+
 /// Allows the pretty printer to break the `break` documents inside the given
 /// group.
 ///

test/glam/doc_test.gleam

@@ -200,3 +200,32 @@ pub fn flex_break_with_group_and_nesting_test() {
   doc.to_string(list, 1)
   |> should.equal("[\n  1,\n  2,\n  3,\n  4,\n  5,\n]")
 }
+
+pub fn zero_width_string_test() {
+  let string_with_break_and_zero_string =
+    [
+      doc.from_string("doc"),
+      doc.break(" ", ""),
+      doc.from_string("with"),
+      doc.break(" ", ""),
+      doc.zero_width_string("zero width"),
+    ]
+    |> doc.concat
+    |> doc.group
+
+  doc.to_string(string_with_break_and_zero_string, 10)
+  |> should.equal("doc with zero width")
+}
+
+pub fn zero_width_string_example_test() {
+  [
+    doc.zero_width_string("\u{001b}[1;31m"),
+    doc.from_string("I'm a red"),
+    doc.break(", ", ","),
+    doc.from_string("bold text"),
+  ]
+  |> doc.concat
+  |> doc.group
+  |> doc.to_string(20)
+  |> should.equal("\u{001b}[1;31mI'm a red, bold text")
+}