handle lexer errors by throwing exception instead of ignoring

andimarek · andimarek · commit 370ee738bdbe · 2019-07-15T17:30:54.000+10:00
diff --git a/src/main/java/graphql/parser/Parser.java b/src/main/java/graphql/parser/Parser.java
@@ -2,11 +2,15 @@
 
 import graphql.Internal;
 import graphql.language.Document;
+import graphql.language.SourceLocation;
 import graphql.parser.antlr.GraphqlLexer;
 import graphql.parser.antlr.GraphqlParser;
+import org.antlr.v4.runtime.BaseErrorListener;
 import org.antlr.v4.runtime.CharStreams;
 import org.antlr.v4.runtime.CodePointCharStream;
 import org.antlr.v4.runtime.CommonTokenStream;
+import org.antlr.v4.runtime.RecognitionException;
+import org.antlr.v4.runtime.Recognizer;
 import org.antlr.v4.runtime.Token;
 import org.antlr.v4.runtime.atn.PredictionMode;
 
@@ -51,6 +55,13 @@ public Document parseDocument(Reader reader) throws InvalidSyntaxException {
         }
 
         GraphqlLexer lexer = new GraphqlLexer(charStream);
+        lexer.removeErrorListeners();
+        lexer.addErrorListener(new BaseErrorListener() {
+            @Override
+            public void syntaxError(Recognizer<?, ?> recognizer, Object offendingSymbol, int line, int charPositionInLine, String msg, RecognitionException e) {
+                throw new InvalidSyntaxException(new SourceLocation(line, charPositionInLine), "Invalid syntax: " + msg, null, null, null);
+            }
+        });
 
         CommonTokenStream tokens = new CommonTokenStream(lexer);
 
diff --git a/src/test/groovy/graphql/parser/ParserTest.groovy b/src/test/groovy/graphql/parser/ParserTest.groovy
@@ -733,4 +733,19 @@ triple3 : """edge cases \\""" "" " \\"" \\" edge cases"""
         fragmentDefinition.name == "Foo"
 
     }
+
+    def "parser should throw syntax errors"() {
+        given:
+        def input = """
+            type Foo {
+              name / String
+            }
+        """
+        when:
+        def document = Parser.parse(input)
+        println document
+        then:
+        def e = thrown(InvalidSyntaxException)
+        e.message.contains("Invalid syntax")
+    }
 }
