Add information on expected tokens to syntax errors

This now mimics the error messages provided by PHP itself (pre 5.4).

CHANGELOG.md

@@ -1,7 +1,11 @@
 Version 0.9.4-dev
 -----------------
 
-Nothing yet.
+* Syntax errors now include information on expected tokens and mimic the format of PHP's own (pre 5.4) error messages.
+  Example:
+
+        Old: Unexpected token T_STATIC on line 1
+        New: Syntax error, unexpected T_STATIC, expecting T_STRING or T_NS_SEPARATOR or '{'
 
 Version 0.9.3 (22.11.2012)
 --------------------------

grammar/kmyacc.php.parser

@@ -304,8 +304,35 @@ class #(-p)
                     $attributeStack[$this->stackPos] = $startAttributes;
                 } else {
                     /* error */
+                    $expected = array();
+
+                    $base = self::$yybase[$state];
+                    for ($i = 0; $i < self::TOKEN_MAP_SIZE; ++$i) {
+                        $n = $base + $i;
+                        if ($n >= 0 && $n < self::YYLAST && self::$yycheck[$n] == $i
+                         || $state < self::YY2TBLSTATE
+                            && ($n = self::$yybase[$state + self::YYNLSTATES] + $i)
+                            && $n < self::YYLAST && self::$yycheck[$n] == $i
+                        ) {
+                            if (self::$yyaction[$n] != self::YYUNEXPECTED) {
+                                if (count($expected) == 4) {
+                                    /* Too many expected tokens */
+                                    $expected = array();
+                                    break;
+                                }
+
+                                $expected[] = self::$terminals[$i];
+                            }
+                        }
+                    }
+
+                    $expectedString = '';
+                    if ($expected) {
+                        $expectedString = ', expecting ' . implode(' or ', $expected);
+                    }
+
                     throw new PHPParser_Error(
-                        'Unexpected token ' . self::$terminals[$tokenId],
+                        'Syntax error, unexpected ' . self::$terminals[$tokenId] . $expectedString,
                         $startAttributes['startLine']
                     );
                 }

lib/PHPParser/Parser.php

@@ -1068,8 +1068,35 @@ class PHPParser_Parser
                     $attributeStack[$this->stackPos] = $startAttributes;
                 } else {
                     /* error */
+                    $expected = array();
+
+                    $base = self::$yybase[$state];
+                    for ($i = 0; $i < self::TOKEN_MAP_SIZE; ++$i) {
+                        $n = $base + $i;
+                        if ($n >= 0 && $n < self::YYLAST && self::$yycheck[$n] == $i
+                         || $state < self::YY2TBLSTATE
+                            && ($n = self::$yybase[$state + self::YYNLSTATES] + $i)
+                            && $n < self::YYLAST && self::$yycheck[$n] == $i
+                        ) {
+                            if (self::$yyaction[$n] != self::YYUNEXPECTED) {
+                                if (count($expected) == 4) {
+                                    /* Too many expected tokens */
+                                    $expected = array();
+                                    break;
+                                }
+
+                                $expected[] = self::$terminals[$i];
+                            }
+                        }
+                    }
+
+                    $expectedString = '';
+                    if ($expected) {
+                        $expectedString = ', expecting ' . implode(' or ', $expected);
+                    }
+
                     throw new PHPParser_Error(
-                        'Unexpected token ' . self::$terminals[$tokenId],
+                        'Syntax error, unexpected ' . self::$terminals[$tokenId] . $expectedString,
                         $startAttributes['startLine']
                     );
                 }

test/code/parser/stmt/class/modifier.test-fail

@@ -26,4 +26,4 @@ Cannot use the final and abstract modifier at the same time on line 1
 -----
 <?php abstract final class A { }
 -----
-Unexpected token T_FINAL on line 1
+Syntax error, unexpected T_FINAL, expecting T_CLASS on line 1

test/code/parser/stmt/class/name.test-fail

@@ -10,7 +10,7 @@ Cannot use "parent" as class name as it is reserved on line 1
 -----
 <?php class static {}
 -----
-Unexpected token T_STATIC on line 1
+Syntax error, unexpected T_STATIC, expecting T_STRING on line 1
 -----
 <?php class A extends self {}
 -----
@@ -22,7 +22,7 @@ Cannot use "parent" as class name as it is reserved on line 1
 -----
 <?php class A extends static {}
 -----
-Unexpected token T_STATIC on line 1
+Syntax error, unexpected T_STATIC, expecting T_STRING or T_NAMESPACE or T_NS_SEPARATOR on line 1
 -----
 <?php class A implements self {}
 -----
@@ -34,7 +34,7 @@ Cannot use "parent" as interface name as it is reserved on line 1
 -----
 <?php class A implements static {}
 -----
-Unexpected token T_STATIC on line 1
+Syntax error, unexpected T_STATIC, expecting T_STRING or T_NAMESPACE or T_NS_SEPARATOR on line 1
 -----
 <?php interface self {}
 -----
@@ -46,7 +46,7 @@ Cannot use "parent" as interface name as it is reserved on line 1
 -----
 <?php interface static {}
 -----
-Unexpected token T_STATIC on line 1
+Syntax error, unexpected T_STATIC, expecting T_STRING on line 1
 -----
 <?php interface A extends self {}
 -----
@@ -58,4 +58,4 @@ Cannot use "parent" as interface name as it is reserved on line 1
 -----
 <?php interface A extends static {}
 -----
-Unexpected token T_STATIC on line 1
+Syntax error, unexpected T_STATIC, expecting T_STRING or T_NAMESPACE or T_NS_SEPARATOR on line 1

test/code/parser/stmt/namespace/name.test-fail

@@ -10,7 +10,7 @@ Cannot use "parent" as namespace name as it is reserved on line 1
 -----
 <?php namespace static;
 -----
-Unexpected token T_STATIC on line 1
+Syntax error, unexpected T_STATIC, expecting T_STRING or T_NS_SEPARATOR or '{' on line 1
 -----
 <?php use A as self;
 -----
@@ -22,4 +22,4 @@ Cannot use "B" as "parent" because "parent" is a special class name on line 1
 -----
 <?php use C as static;
 -----
-Unexpected token T_STATIC on line 1
+Syntax error, unexpected T_STATIC, expecting T_STRING on line 1