fix: correct escape & anchor handling in likeToRegex/regexToLike (#1174)

* fix: correct escape & anchor handling in likeToRegex/regexToLike
- treat \% \_ as literals, escape regex metachars, strip outer ^/$ only
- add unit tests to guarantee accurate LIKE ↔ regex round-trips

* Fix code format

Signed-off-by: Marvin Froeder <[email protected]>

---------

Signed-off-by: Marvin Froeder <[email protected]>
Co-authored-by: Marvin Froeder <[email protected]>

Author: renechoi

querydsl-libraries/querydsl-core/src/main/java/com/querydsl/core/types/ExpressionUtils.java

@@ -529,8 +529,21 @@ public static Expression<String> likeToRegex(Expression<String> expr, boolean ma
       if (matchStartAndEnd && !like.startsWith("%")) {
         rv.append('^');
       }
+      boolean escape = false;
       for (var i = 0; i < like.length(); i++) {
         var ch = like.charAt(i);
+        if (escape) {
+          if (ch == '.' || ch == '*' || ch == '?') {
+            rv.append('\\');
+          }
+          rv.append(ch);
+          escape = false;
+          continue;
+        }
+        if (ch == '\\') {
+          escape = true;
+          continue;
+        }
         if (ch == '.' || ch == '*' || ch == '?') {
           rv.append('\\');
         } else if (ch == '%') {
@@ -601,12 +614,23 @@ public static <T> Expression<T> list(Class<T> clazz, List<? extends Expression<?
   public static Expression<String> regexToLike(Expression<String> expr) {
     if (expr instanceof Constant<?>) {
       final var str = expr.toString();
-      final var rv = new StringBuilder(str.length() + 2);
+      // final var rv = new StringBuilder(str.length() + 2);
+      int start = 0;
+      int end = str.length();
+      if (start < end && str.charAt(start) == '^') {
+        start++;
+      }
+      if (end > start && str.charAt(end - 1) == '$') {
+        end--;
+      }
+      final var rv = new StringBuilder(end - start + 2);
       var escape = false;
-      for (var i = 0; i < str.length(); i++) {
+      // for (var i = 0; i < str.length(); i++) {
+      for (var i = start; i < end; i++) {
         final var ch = str.charAt(i);
         if (!escape && ch == '.') {
-          if (i < str.length() - 1 && str.charAt(i + 1) == '*') {
+          // if (i < str.length() - 1 && str.charAt(i + 1) == '*') {
+          if (i < end - 1 && str.charAt(i + 1) == '*') {
             rv.append('%');
             i++;
           } else {
@@ -616,16 +640,23 @@ public static Expression<String> regexToLike(Expression<String> expr) {
         } else if (!escape && ch == '\\') {
           escape = true;
           continue;
-        } else if (!escape && (ch == '[' || ch == ']' || ch == '^' || ch == '.' || ch == '*')) {
+          // } else if (!escape && (ch == '[' || ch == ']' || ch == '^' || ch == '.' || ch == '*'))
+          // {
+        } else if (!escape
+            && (ch == '[' || ch == ']' || ch == '^' || ch == '$' || ch == '.' || ch == '*')) {
           throw new QueryException("'" + str + "' can't be converted to like form");
         } else if (escape
             && (ch == 'd' || ch == 'D' || ch == 's' || ch == 'S' || ch == 'w' || ch == 'W')) {
           throw new QueryException("'" + str + "' can't be converted to like form");
         }
+        if (ch == '%' || ch == '_') {
+          rv.append('\\');
+        }
         rv.append(ch);
         escape = false;
       }
-      if (!rv.toString().equals(str)) {
+      // if (!rv.toString().equals(str)) {
+      if (start != 0 || end != str.length() || !rv.toString().equals(str.substring(start, end))) {
         return ConstantImpl.create(rv.toString());
       }
     } else if (expr instanceof Operation<?>) {

querydsl-libraries/querydsl-core/src/test/java/com/querydsl/core/types/ExpressionUtilsTest.java

@@ -71,6 +71,19 @@ public void likeToRegex_escape() {
     assertThat(regex(ConstantImpl.create("."))).isEqualTo("^\\.$");
   }
 
+  @Test
+  public void likeToRegex_escapeCharacter() {
+    assertThat(regex(ConstantImpl.create("a\\%b"))).isEqualTo("^a%b$");
+    assertThat(regex(ConstantImpl.create("a\\_b"))).isEqualTo("^a_b$");
+  }
+
+  @Test
+  public void regexToLike_anchorsAndEscapes() {
+    assertThat(like(ConstantImpl.create("^a%b$"))).isEqualTo("a\\%b");
+    assertThat(like(ConstantImpl.create("^a_b$"))).isEqualTo("a\\_b");
+    assertThat(like(ConstantImpl.create("^ab$"))).isEqualTo("ab");
+  }
+
   @Test
   public void regexToLike() {
     assertThat(like(ConstantImpl.create(".*"))).isEqualTo("%");