4 files changed, 49 insertions, 10 deletions
diff --git a/tikzit/src/common/NSString+Tikz.h b/tikzit/src/common/NSString+Tikz.h
index 639e269..ea6ea40 100644
--- a/tikzit/src/common/NSString+Tikz.h
+++ b/tikzit/src/common/NSString+Tikz.h
@@ -19,7 +19,8 @@
 
 @interface NSString (Tikz)
 	- (NSString*) tikzEscapedString;
-	- (BOOL)      isValidTikz;
+	- (BOOL)      isValidTikzPropertyNameOrValue;
+	- (BOOL)      isValidAnchor;
 @end
 
 // vi:ft=objc:noet:ts=4:sts=4:sw=4
diff --git a/tikzit/src/common/NSString+Tikz.m b/tikzit/src/common/NSString+Tikz.m
index 8b11ad2..520ffd3 100644
--- a/tikzit/src/common/NSString+Tikz.m
+++ b/tikzit/src/common/NSString+Tikz.m
@@ -16,6 +16,7 @@
  */
 
 #import "NSString+Tikz.h"
+#import "TikzGraphAssembler.h"
 
 @implementation NSString (Tikz)
 
@@ -31,7 +32,7 @@
 	}
 }
 
-- (BOOL) isValidTikz {
+- (BOOL) isValidTikzPropertyNameOrValue {
 	NSUInteger length = [self length];
 	unsigned int brace_depth = 0;
 	unsigned int escape = 0;
@@ -53,6 +54,10 @@
 	return !escape && brace_depth == 0;
 }
 
+- (BOOL) isValidAnchor {
+	return [TikzGraphAssembler validateTikzEdgeAnchor:self];
+}
+
 @end
 
 // vi:ft=objc:noet:ts=4:sts=4:sw=4
diff --git a/tikzit/src/common/TikzGraphAssembler.h b/tikzit/src/common/TikzGraphAssembler.h
index c365128..3403969 100644
--- a/tikzit/src/common/TikzGraphAssembler.h
+++ b/tikzit/src/common/TikzGraphAssembler.h
@@ -100,6 +100,16 @@
  */
 + (BOOL)validateTikzPropertyNameOrValue:(NSString*)tikz;
 
+/**
+ * Validate an edge anchor
+ *
+ * Checks that the given string will successfully lex if used as an anchor for
+ * and edge
+ * @param tikz   the string to validate
+ * @return       YES if the string can be used as an edge anchor, NO otherwise
+ */
++ (BOOL)validateTikzEdgeAnchor:(NSString*)tikz;
+
 @end
 
 // vi:ft=objc:noet:ts=4:sts=4:sw=4
diff --git a/tikzit/src/common/TikzGraphAssembler.m b/tikzit/src/common/TikzGraphAssembler.m
index c49298f..6b191a2 100644
--- a/tikzit/src/common/TikzGraphAssembler.m
+++ b/tikzit/src/common/TikzGraphAssembler.m
@@ -113,21 +113,44 @@
 }
 
 + (BOOL)validateTikzPropertyNameOrValue:(NSString*)tikz {
-    BOOL r;
-    
-    NSString * testTikz = [NSString stringWithFormat: @"{%@}", tikz];
-    
+	BOOL valid;
+	
+	NSString * testTikz = [NSString stringWithFormat: @"{%@}", tikz];
+	
 	void *scanner;
 	yylex_init (&scanner);
 	yyset_extra(nil, scanner);
 	yy_scan_string([testTikz UTF8String], scanner);
 	YYSTYPE lval;
 	YYLTYPE lloc;
-	yylex(&lval, &lloc, scanner);
-    r = !(yyget_leng(scanner) < [testTikz length]);
+	int result = yylex(&lval, &lloc, scanner);
+	valid = (result == DELIMITEDSTRING) &&
+		    (yyget_leng(scanner) == [testTikz length]);
 	yylex_destroy(scanner);
-    
-    return r;
+	
+    return valid;
+}
+
++ (BOOL)validateTikzEdgeAnchor:(NSString*)tikz {
+	BOOL valid = YES;
+	
+	NSString * testTikz = [NSString stringWithFormat: @"(1.%@)", tikz];
+	
+	void *scanner;
+	yylex_init (&scanner);
+	yyset_extra(nil, scanner);
+	yy_scan_string([testTikz UTF8String], scanner);
+	YYSTYPE lval;
+	YYLTYPE lloc;
+	valid = valid && (yylex(&lval, &lloc, scanner) == LEFTPARENTHESIS);
+	valid = valid && (yylex(&lval, &lloc, scanner) == REFSTRING);
+	valid = valid && (yylex(&lval, &lloc, scanner) == FULLSTOP);
+	valid = valid && (yylex(&lval, &lloc, scanner) == REFSTRING);
+	valid = valid && (yylex(&lval, &lloc, scanner) == RIGHTPARENTHESIS);
+	valid = valid && (lloc.last_column == [testTikz length]);
+	yylex_destroy(scanner);
+	
+    return valid;
 }
 
 @end