Fix like expression (#381)

Signed-off-by: Francesco Guardiani <francescoguard@gmail.com>

Author: slinkydeveloper

sql/src/main/java/io/cloudevents/sql/impl/expressions/LikeExpression.java

@@ -17,12 +17,7 @@ public LikeExpression(Interval expressionInterval, String expressionText, Expres
         super(expressionInterval, expressionText);
         this.internal = internal;
         // Converting to regex is not the most performant impl, but it works
-        this.pattern = Pattern.compile("^" +
-            pattern.replaceAll("(?<!\\\\)\\%", ".*")
-                .replaceAll("(?<!\\\\)\\_", ".")
-                .replaceAll("\\\\\\%", "%")
-                .replaceAll("\\\\_", "_") + "$"
-        );
+        this.pattern = convertLikePatternToRegex(pattern);
     }
 
     @Override
@@ -35,4 +30,38 @@ public Object evaluate(EvaluationRuntime runtime, CloudEvent event, ExceptionThr
 
         return pattern.matcher(value).matches();
     }
+
+    private Pattern convertLikePatternToRegex(String pattern) {
+        StringBuilder builder = new StringBuilder();
+        builder.append("^\\Q");
+
+        for (int i = 0; i < pattern.length(); i++) {
+            if (pattern.charAt(i) == '\\' && i < pattern.length() - 1) {
+                if (pattern.charAt(i + 1) == '%') {
+                    // \% case
+                    builder.append('%');
+                    i++;
+                    continue;
+                } else if (pattern.charAt(i + 1) == '_') {
+                    // \_ case
+                    builder.append('_');
+                    i++;
+                    continue;
+                }
+            }
+            if (pattern.charAt(i) == '_') {
+                // replace with .
+                builder.append("\\E.\\Q");
+            } else if (pattern.charAt(i) == '%') {
+                // replace with .*
+                builder.append("\\E.*\\Q");
+            } else {
+                builder.append(pattern.charAt(i));
+            }
+        }
+
+        builder.append("\\E$");
+
+        return Pattern.compile(builder.toString());
+    }
 }

sql/src/test/resources/tck/like_expression.yaml

@@ -1,8 +1,11 @@
 name: Like expression
 tests:
-  - name: Exact match
+  - name: Exact match (1)
     expression: "'abc' LIKE 'abc'"
     result: true
+  - name: Exact match (2)
+    expression: "'ab\\c' LIKE 'ab\\c'"
+    result: true
   - name: Exact match (negate)
     expression: "'abc' NOT LIKE 'abc'"
     result: false
@@ -25,6 +28,12 @@ tests:
   - name: Percentage operator (6)
     expression: "'' LIKE 'abc'"
     result: false
+  - name: Percentage operator (7)
+    expression: "'.ab.cde.' LIKE '.%.%.'"
+    result: true
+  - name: Percentage operator (8)
+    expression: "'ab.cde' LIKE '.%.%.'"
+    result: false
 
   - name: Underscore operator (1)
     expression: "'abc' LIKE 'a_b_c'"
@@ -41,6 +50,12 @@ tests:
   - name: Underscore operator (5)
     expression: "'azbzc' LIKE 'a_b_c'"
     result: true
+  - name: Underscore operator (6)
+    expression: "'.a.b.' LIKE '._._.'"
+    result: true
+  - name: Underscore operator (7)
+    expression: "'abcd.' LIKE '._._.'"
+    result: false
 
   - name: Escaped underscore wildcards (1)
     expression: "'a_b_c' LIKE 'a\\_b\\_c'"