Not wrap strings at escape backslash (#4524)

* Issue #4471 - not wrap strings at backslash

* Changes according to comments to the fix PR #4524

* Some more modifications to improve the code per comments received

Author: davidBar-On

src/formatting/string.rs

@@ -226,6 +226,24 @@ fn not_whitespace_except_line_feed(g: &str) -> bool {
 /// FIXME(issue#3281): We must follow UAX#14 algorithm instead of this.
 fn break_string(max_width: usize, trim_end: bool, line_end: &str, input: &[&str]) -> SnippetState {
     let break_at = |index /* grapheme at index is included */| {
+        // Ensure break is not after an escape '\' as it will "escape" the `\` that is added
+        // for concatenating the two parts of the broken line.
+        let index = if input[index] != "\\" {
+            index
+        } else {
+            let index_offset = match input[0..index]
+                .iter()
+                .rposition(|grapheme| grapheme.ne(&"\\"))
+            {
+                // There is a non-`\` to the left
+                Some(non_backslash_index) => (index - non_backslash_index) % 2,
+                // Only `\` to the left
+                None => index % 2,
+            };
+            // Make sure break is after even number (including zero) of `\`
+            index - index_offset
+        };
+
         // Take in any whitespaces to the left/right of `input[index]` while
         // preserving line feeds
         let index_minus_ws = input[0..=index]

tests/source/string-lit.rs

@@ -59,3 +59,12 @@ fn issue_1282() {
 // #1987
 #[link_args = "-s NO_FILESYSTEM=1 -s NO_EXIT_RUNTIME=1 -s EXPORTED_RUNTIME_METHODS=[\"_malloc\"] -s NO_DYNAMIC_EXECUTION=1 -s ELIMINATE_DUPLICATE_FUNCTIONS=1 -s EVAL_CTORS=1"]
 extern "C" {}
+
+// #4471 - strings including `\` shaouldnot wrap at the `\`
+const ASCII_ESCAPE: &str = "id\u{1f}1\u{1f}/Users/nixon/dev/rs/gitstatusd\u{1f}1c9be4fe5460a30e70de9cbf99c3ec7064296b28\u{1f}master\u{1f}\u{1f}\u{1f}\u{1f}\u{1f}7\u{1f}0\u{1f}1\u{1f}0\u{1f}1\u{1f}0\u{1f}0\u{1f}0\u{1f}\u{1f}0\u{1f}0\u{1f}0\u{1f}\u{1f}\u{1f}0\u{1f}0\u{1f}0\u{1f}0";
+const ASCII_ESCAPE: &str = "id\u{1f}1\u{1f}/Users/nixon/dev/rs/gitstatusd\u{1f}1c9be4fe5460a30e70de9cbf99c3ec7064296b28\u{1f}master\u{1f}\u{1f}\u{1f}\u{1f}\u{1f}7\u{1f}0";
+const ASCII_ESCAPE: &str = "id\u{1f}1\u{1f}/Users/nixon/dev/rs/gitstatusd\u{1f}1c9be4fe5460a30e70de9cbf99c3ec70642,96b28\u{1f}master\u{1f}\u{1f}\u{1f}\u{1f}\u{1f}7\u{1f}0";
+const ASCII_ESCAPE: &str = "id\u{1f}1\u{1f}/Users/nixon/dev/rs/gitstatusd\u{1f}1c9be4fe5460a30e70de9cbf99c3ec70642 96b28\u{1f}master\u{1f}\u{1f}\u{1f}\u{1f}\u{1f}7\u{1f}0";
+const ASCII_ESCAPE: &str = "\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\";
+const ASCII: &str = "xxxxxxxxxxxxxxxxxxxxxxxxxx\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\";
+const ASCII: &str = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\\\nyyyyyyyyyyyy";

tests/target/string-lit.rs

@@ -61,3 +61,26 @@ fn issue_1282() {
 #[link_args = "-s NO_FILESYSTEM=1 -s NO_EXIT_RUNTIME=1 -s EXPORTED_RUNTIME_METHODS=[\"_malloc\"] \
                -s NO_DYNAMIC_EXECUTION=1 -s ELIMINATE_DUPLICATE_FUNCTIONS=1 -s EVAL_CTORS=1"]
 extern "C" {}
+
+// #4471 - strings including `\` shaouldnot wrap at the `\`
+const ASCII_ESCAPE: &str =
+    "id\u{1f}1\u{1f}/Users/nixon/dev/rs/gitstatusd\u{1f}1c9be4fe5460a30e70de9cbf99c3ec7064296b28\
+     \u{1f}master\u{1f}\u{1f}\u{1f}\u{1f}\u{1f}7\u{1f}0\u{1f}1\u{1f}0\u{1f}1\u{1f}0\u{1f}0\u{1f}0\
+     \u{1f}\u{1f}0\u{1f}0\u{1f}0\u{1f}\u{1f}\u{1f}0\u{1f}0\u{1f}0\u{1f}0";
+const ASCII_ESCAPE: &str = "id\u{1f}1\u{1f}/Users/nixon/dev/rs/gitstatusd\
+                            \u{1f}1c9be4fe5460a30e70de9cbf99c3ec7064296b28\u{1f}master\u{1f}\
+                            \u{1f}\u{1f}\u{1f}\u{1f}7\u{1f}0";
+const ASCII_ESCAPE: &str = "id\u{1f}1\u{1f}/Users/nixon/dev/rs/gitstatusd\
+                            \u{1f}1c9be4fe5460a30e70de9cbf99c3ec70642,96b28\u{1f}master\u{1f}\
+                            \u{1f}\u{1f}\u{1f}\u{1f}7\u{1f}0";
+const ASCII_ESCAPE: &str = "id\u{1f}1\u{1f}/Users/nixon/dev/rs/gitstatusd\
+                            \u{1f}1c9be4fe5460a30e70de9cbf99c3ec70642 \
+                            96b28\u{1f}master\u{1f}\u{1f}\u{1f}\u{1f}\u{1f}7\u{1f}0";
+const ASCII_ESCAPE: &str = "\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
+                            \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
+                            \\";
+const ASCII: &str = "xxxxxxxxxxxxxxxxxxxxxxxxxx\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
+                     \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\";
+const ASCII: &str =
+    "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\\\
+     \nyyyyyyyyyyyy";