\n and \t handling - fixes #52

allegro · Jun 27, 2024 · e09a5b1 · e09a5b1
1 parent 49ee4b0
commit e09a5b1
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Showing 2 changed files with 55 additions and 11 deletions.
diff --git a/src/main/java/pl/allegro/tech/opel/OpelParser.java b/src/main/java/pl/allegro/tech/opel/OpelParser.java
@@ -7,10 +7,14 @@
 import org.parboiled.annotations.SuppressSubnodes;
 
 import java.math.BigDecimal;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 @BuildParseTree
 public class OpelParser extends BaseParser<OpelNode> {
 
+    private final Pattern escapeCharacterPattern = Pattern.compile("\\\\.");
+
     final ImplicitConversion implicitConversion;
     final OpelNodeFactory nodeFactory;
 
@@ -343,14 +347,36 @@ protected Rule fromStringLiteral(String string) {
         return String(string).label("'" + string + "'");
     }
 
+    /**
+     * Escapes special characters in string literals.
+     * Explicitly converts \t and \n to their corresponding whitespace characters.
+     * All other escaped characters are left as they are.
+     */
     protected String escapeString(String string) {
+        Matcher matcher = escapeCharacterPattern.matcher(string);
         StringBuilder result = new StringBuilder();
-        for (int i = 0; i < string.length(); i++) {
-            if (string.charAt(i) == '\\') {
-                i++;
+        while (matcher.find()) {
+            String replacement;
+            switch (matcher.group()) {
+                case "\\t":
+                    replacement = "\t";
+                    break;
+                case "\\r":
+                    replacement = "\r";
+                    break;
+                case "\\n":
+                    replacement = "\n";
+                    break;
+                case "\\\\":
+                    replacement = "\\\\";
+                    break;
+                default:
+                    replacement = matcher.group().substring(1);
+                    break;
             }
-            result.append(string.charAt(i));
+            matcher.appendReplacement(result, replacement);
         }
+        matcher.appendTail(result);
         return result.toString();
     }
 

diff --git a/src/test/groovy/pl/allegro/tech/opel/OpelEngineIntegrationSpec.groovy b/src/test/groovy/pl/allegro/tech/opel/OpelEngineIntegrationSpec.groovy
@@ -7,7 +7,6 @@ import java.util.concurrent.CompletableFuture
 import java.util.concurrent.ExecutionException
 
 import static OpelEngineBuilder.create
-import static pl.allegro.tech.opel.TestUtil.constFunctionReturning
 import static pl.allegro.tech.opel.TestUtil.functions
 
 class OpelEngineIntegrationSpec extends Specification {
@@ -74,9 +73,9 @@ xyz'"""
     def 'should evaluate expression with whitespaces "#input"'() {
         given:
         def engine = create()
-                    .withImplicitConversion(String, BigDecimal, { string -> new BigDecimal(string) })
-                    .withImplicitConversion(BigDecimal, String, { decimal -> decimal.toPlainString() })
-                    .build()
+                .withImplicitConversion(String, BigDecimal, { string -> new BigDecimal(string) })
+                .withImplicitConversion(BigDecimal, String, { decimal -> decimal.toPlainString() })
+                .build()
 
         expect:
         engine.eval(input).get() == expResult
@@ -109,9 +108,9 @@ xyz'"""
     def 'should evaluate expression which starts with whitespace(s): "#input"'() {
         given:
         def engine = create()
-                    .withImplicitConversion(String, BigDecimal, { string -> new BigDecimal(string) })
-                    .withImplicitConversion(BigDecimal, String, { decimal -> decimal.toPlainString() })
-                    .build()
+                .withImplicitConversion(String, BigDecimal, { string -> new BigDecimal(string) })
+                .withImplicitConversion(BigDecimal, String, { decimal -> decimal.toPlainString() })
+                .build()
 
         expect:
         engine.eval(input).get() == expResult
@@ -305,4 +304,23 @@ xyz'"""
         counter1 == 1
         counter2 == 0
     }
+
+    @Unroll
+    def 'should not treat \\n and \\t characters as escaped but as whitespace control characters'() {
+        given:
+        def engine = create().build()
+
+        expect:
+        engine.eval(input).get() == expResult
+
+        where:
+        input                                       || expResult
+        /'Guns\'n\'Roses'.startsWith('Guns\'n\'R')/ || true //\' is an escaped character
+        /'\\slash\\'.startsWith('\\')/              || true //\\ is an escaped character
+        /'pest'.startsWith('\pest')/                || true //\p is an escaped character
+        /'test'.startsWith('\test')/                || false //\t is replaced by tab character
+        /'nest'.startsWith('\nest')/                || false //\n is replaced by newline character
+        /'rest'.startsWith('\rest')/                || false //\r is replaced by RF character
+        /'rust'.startsWith('\r\nust')/              || false //\r\n is replaced with newline character
+    }
 }