From 2d0a1ef2b802a4a466f27133629182b784029f9f Mon Sep 17 00:00:00 2001
From: hdwalters <huw.walters@gmail.com>
Date: Wed, 11 Sep 2024 20:28:56 +0100
Subject: [PATCH] Optionally use sed extended regex syntax (#453)

* Optionally use sed extended regex syntax.

* Update src/std/text.ab

Co-authored-by: Phoenix Himself <pkaras.it@gmail.com>

* Add comment stating that sed extended regex may fail on some older Linux variants.

* Change regex used to detect GNU sed.

* Remove duplicate unsafe from stdlib function.

---------

Co-authored-by: Phoenix Himself <pkaras.it@gmail.com>
---
 src/std/text.ab                         | 19 +++++++++++++++----
 src/tests/stdlib/replace_regex.ab       |  8 --------
 src/tests/stdlib/replace_regex_basic.ab |  8 ++++++++
 src/tests/stdlib/replace_regex_ext.ab   | 10 ++++++++++
 4 files changed, 33 insertions(+), 12 deletions(-)
 delete mode 100644 src/tests/stdlib/replace_regex.ab
 create mode 100644 src/tests/stdlib/replace_regex_basic.ab
 create mode 100644 src/tests/stdlib/replace_regex_ext.ab

diff --git a/src/std/text.ab b/src/std/text.ab
index 681b45dec..7a96bc120 100644
--- a/src/std/text.ab
+++ b/src/std/text.ab
@@ -11,11 +11,22 @@ pub fun replace(source, pattern, replacement) {
 /// Replaces all occurences of a regex pattern in the content with the provided replacement text.
 ///
 /// Function uses `sed`
-pub fun replace_regex(source: Text, pattern: Text, replacement: Text): Text {
-    return unsafe $echo "{source}" | sed -e "s/{pattern}/{replacement}/g"$
+pub fun replace_regex(source: Text, pattern: Text, replacement: Text, extended: Bool = false): Text {
+    unsafe {
+        if extended {
+            // GNU sed versions 4.0 through 4.2 support extended regex syntax,
+            // but only via the "-r" option; use that if the version information
+            // contains "GNU sed".
+            $re='\bCopyright\b.+\bFree Software Foundation\b'; [[ \$(sed --version 2>/dev/null) =~ \$re ]]$
+            let flag = status == 0 then "-r" else "-E"
+            return $echo "{source}" | sed {flag} -e "s/{pattern}/{replacement}/g"$
+        } else {
+            return $echo "{source}" | sed -e "s/{pattern}/{replacement}/g"$
+        }
+    }
 }
 
-/// Splits the input `text` into an array of substrings using the specified `delimiter`. 
+/// Splits the input `text` into an array of substrings using the specified `delimiter`.
 pub fun split(text: Text, delimiter: Text): [Text] {
     let result = [Text]
     unsafe $IFS="{delimiter}" read -rd '' -a {nameof result} < <(printf %s "\${nameof text}")$
@@ -29,7 +40,7 @@ pub fun lines(text: Text): [Text] {
 
 /// Splits a `text` into an array of substrings based on space character.
 pub fun words(text: Text): [Text] {
-  return split(text, " ")
+    return split(text, " ")
 }
 
 /// Merges text using the delimeter specified.
diff --git a/src/tests/stdlib/replace_regex.ab b/src/tests/stdlib/replace_regex.ab
deleted file mode 100644
index ef3068c28..000000000
--- a/src/tests/stdlib/replace_regex.ab
+++ /dev/null
@@ -1,8 +0,0 @@
-import * from "std/text"
-
-// Output
-// abc456def
-
-main {
-    echo replace_regex("abc123def", "[0-9][0-9]*", "456")
-}
diff --git a/src/tests/stdlib/replace_regex_basic.ab b/src/tests/stdlib/replace_regex_basic.ab
new file mode 100644
index 000000000..7569fb0e4
--- /dev/null
+++ b/src/tests/stdlib/replace_regex_basic.ab
@@ -0,0 +1,8 @@
+import * from "std/text"
+
+// Output
+// abc[123]def
+
+main {
+    echo replace_regex("abc123def", "\([0-9][0-9]*\)", "[\1]")
+}
diff --git a/src/tests/stdlib/replace_regex_ext.ab b/src/tests/stdlib/replace_regex_ext.ab
new file mode 100644
index 000000000..50c3c88e5
--- /dev/null
+++ b/src/tests/stdlib/replace_regex_ext.ab
@@ -0,0 +1,10 @@
+import * from "std/text"
+
+// Output
+// abc[123]def
+
+main {
+    // This will fail on any system where sed does not support extended
+    // regex syntax, via "-r" on GNU sed and "-E" on all other versions.
+    echo replace_regex("abc123def", "([0-9]+)", "[\1]", true)
+}