From 6bd40f05077bbd61088510a4c12bb32931831457 Mon Sep 17 00:00:00 2001
From: "l.gualtieri" <luigi.gualtieri@gmail.com>
Date: Tue, 11 Feb 2025 19:03:17 +0100
Subject: [PATCH] Add support for REGEXP_REPLACE in limbo extension #740

---
 extensions/regexp/src/lib.rs | 28 +++++++++++++++++++++++++++-
 testing/extensions.py        | 15 +++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/extensions/regexp/src/lib.rs b/extensions/regexp/src/lib.rs
index 6f037e4d4..ce9b6d2ee 100644
--- a/extensions/regexp/src/lib.rs
+++ b/extensions/regexp/src/lib.rs
@@ -2,7 +2,7 @@ use limbo_ext::{register_extension, scalar, Value, ValueType};
 use regex::Regex;
 
 register_extension! {
-    scalars: { regexp, regexp_like, regexp_substr }
+    scalars: { regexp, regexp_like, regexp_substr, regexp_replace }
 }
 
 #[scalar(name = "regexp")]
@@ -56,3 +56,29 @@ fn regexp_substr(&self, args: &[Value]) -> Value {
         _ => Value::null(),
     }
 }
+
+#[scalar(name = "regexp_replace")]
+fn regexp_replace(&self, args: &[Value]) -> Value {
+    let replacement = match args.get(2) {
+        Some(repl) => repl.to_text().unwrap_or_default(),
+        None => "", // If args[2] does not exist, use an empty string
+    };
+
+    match (args.get(0), args.get(1)) {
+        (Some(haystack), Some(pattern)) => {
+            let Some(haystack_text) = haystack.to_text() else {
+                return Value::from_text("".to_string()); // Return an empty string if haystack is not valid
+            };
+            let Some(pattern_text) = pattern.to_text() else {
+                return Value::from_text("".to_string()); // Return an empty string if pattern is not valid
+            };
+
+            let re = match Regex::new(&pattern_text) {
+                Ok(re) => re,
+                Err(_) => return Value::from_text("".to_string()), // Return an empty string if regex compilation fails
+            };
+            Value::from_text(re.replace(&haystack_text, replacement).to_string())
+        }
+        _ => Value::from_text("".to_string()), // Return an empty string for invalid value types
+    }
+}
diff --git a/testing/extensions.py b/testing/extensions.py
index 77ecbc703..76af242dd 100755
--- a/testing/extensions.py
+++ b/testing/extensions.py
@@ -190,6 +190,21 @@ def test_regexp(pipe):
     run_test(
         pipe, "SELECT regexp_substr('the year is unknow', '[0-9]+');", returns_null
     )
+    run_test(
+        pipe,
+        "select regexp_replace('the year is 2021', '[0-9]+', '2050') = 'the year is 2050';",
+        validate_true,
+    )
+    run_test(
+        pipe,
+        "select regexp_replace('the year is 2021', '2k21', '2050') = 'the year is 2021';",
+        validate_true,
+    )
+    run_test(
+        pipe,
+        "select regexp_replace('the year is 2021', '([0-9]+)', '$1 or 2050') = 'the year is 2021 or 2050';",
+        validate_true,
+    )
 
 
 def validate_median(res):