diff options
Diffstat (limited to 'chapter17/src/main')
| -rw-r--r-- | chapter17/src/main/java/com/seaofnodes/simple/Parser.java | 49 |
1 files changed, 41 insertions, 8 deletions
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/Parser.java b/chapter17/src/main/java/com/seaofnodes/simple/Parser.java index 09ea21ac..47e7c3bb 100644 --- a/chapter17/src/main/java/com/seaofnodes/simple/Parser.java +++ b/chapter17/src/main/java/com/seaofnodes/simple/Parser.java @@ -889,13 +889,30 @@ public class Parser { if( matchx("new" ) ) return alloc(); // Expect an identifier now ScopeMinNode.Var n = requireLookupId("an identifier or expression"); - Node rvalue = _scope.in(n).keep(); - if( matchx("++") || matchx("--") ) { - if( n._final ) - throw error("Cannot reassign final '"+n._name+"'"); - _scope.update(n,zsMask(peep(new AddNode(rvalue,con( _lexer.peek(-1)=='+' ? 1 : -1))),n.type())); - } - return rvalue.unkeep(); + Node rvalue = _scope.in(n); + // Check for assign-update, x += e0; + char ch = _lexer.matchOperAssign(); + if( ch==0 ) return rvalue; + if( n._final ) + throw error("Cannot reassign final '"+n._name+"'"); + Node op = switch(ch) { + case '+' -> new AddNode(rvalue,null); + case '-' -> new SubNode(rvalue,null); + case '*' -> new MulNode(rvalue,null); + case '/' -> new DivNode(rvalue,null); + case 1 -> new AddNode(rvalue,con( 1)); + case (char)-1 -> new AddNode(rvalue,con(-1)); + default -> throw Utils.TODO(); + }; + // Return pre-value (x+=1) or post-value (x++) + boolean pre = op.in(2)==null; + // Parse RHS argument as needed + if( pre ) + { op.keep().setDef(2,parseExpression()); op.unkeep(); } + else rvalue.keep(); // Keep post-value across peeps + op = zsMask(peep(op),n.type()); + _scope.update(n,op); + return pre ? op : rvalue.unkeep(); } ScopeMinNode.Var requireLookupId(String msg) { @@ -1344,12 +1361,28 @@ public class Parser { // private boolean isPunctuation(char ch) { - return "=;[]<>()+-/*".indexOf(ch) != -1; + return "=;[]<>()+-/*&|^".indexOf(ch) != -1; } private String parsePunctuation() { int start = _position; return new String(_input, start, 1); } + + // Next oper= character, or 0. + // As a convenience, mark "++" as a char 1 and "--" as char -1 (65535) + public char matchOperAssign() { + skipWhiteSpace(); + if( _position+2 >= _input.length ) return 0; + char ch0 = (char)_input[_position]; + if( "+-/*&|^".indexOf(ch0) == -1 ) return 0; + char ch1 = (char)_input[_position+1]; + if( ch1=='=' ) + { _position += 2; return ch0; } + if( isIdLetter((char)_input[_position+2]) ) return 0; // Stop --x + if( ch0 == '+' && ch1 == '+' ) { _position += 2; return (char) 1; } + if( ch0 == '-' && ch1 == '-' ) { _position += 2; return (char)-1; } + return 0; + } } } |