Test for "arg--2"

Parse as "arg - -2" and not "arg--  2" which is a syntax error

2 files changed, 8 insertions, 0 deletions

diff --git a/chapter17/src/main/java/com/seaofnodes/simple/Parser.java b/chapter17/src/main/java/com/seaofnodes/simple/Parser.java
index 1cdf27fb..570ae67e 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/Parser.java
@@ -1412,6 +1412,7 @@ public class Parser {
 
         // Next oper= character, or 0.
         // As a convenience, mark "++" as a char 1 and "--" as char -1 (65535)
+        // Disallow e.g. "arg--1" which should parse as "arg - -1"
         public char matchOperAssign() {
             skipWhiteSpace();
             if( _position+2 >= _input.length ) return 0;
@@ -1419,6 +1420,7 @@ public class Parser {
             if( "+-/*&|^".indexOf(ch0) == -1 ) return 0;
             char ch1 = (char)_input[_position+1];
             if(               ch1 == '=' ) { _position += 2; return ch0; }
+            if( Character.isDigit(_input[_position+2]) ) return 0;
             if( ch0 == '+' && ch1 == '+' ) { _position += 2; return (char) 1; }
             if( ch0 == '-' && ch1 == '-' ) { _position += 2; return (char)-1; }
             return 0;
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter04Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter04Test.java
index 24612fee..0db3afde 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter04Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter04Test.java
@@ -125,4 +125,10 @@ public class Chapter04Test {
         assertEquals("return (-arg);", ret.print());
     }
 
+    @Test
+    public void testBug5() {
+        Parser parser = new Parser("return arg--2;");
+        StopNode ret = parser.parse();
+        assertEquals("return (arg--2);", ret.print());
+    }
 }