Closes PY-31 "Unclosed string literals are not highlighted as erorrs".

python/src/com/jetbrains/python/PythonLanguage.java

@@ -36,6 +36,7 @@ public class PythonLanguage extends Language {
     _annotators.add(DocStringAnnotator.class);
     _annotators.add(ImportAnnotator.class);
     _annotators.add(UnresolvedReferenceAnnotator.class);
+    _annotators.add(StringConstantAnnotator.class);
   }
 
 

python/src/com/jetbrains/python/validation/StringConstantAnnotator.java

@@ -0,0 +1,53 @@
+package com.jetbrains.python.validation;
+
+import com.jetbrains.python.psi.PyStringLiteralExpression;
+
+/**
+ * Looks for well-formedness of string constants.
+ * User: dcheryasov
+ * Date: Jul 5, 2008
+ * Time: 11:58:57 PM
+ */
+public class StringConstantAnnotator extends PyAnnotator {
+  public void visitPyStringLiteralExpression(final PyStringLiteralExpression node) {
+    String s = node.getText();
+    String msg = "";
+    boolean ok = true;
+    boolean esc = false;
+    int index = 0;
+    // skip 'unicode' and 'raw' modifiers
+    char first_quote = s.charAt(index);
+    if ((first_quote == 'u') || (first_quote == 'U')) index += 1;
+    first_quote = s.charAt(index);
+    if ((first_quote == 'r') || (first_quote == 'R')) index += 1;
+    first_quote = s.charAt(index);
+    // s can't begin with non-quote, else parser would not say it's a string
+    index += 1;
+    if (index >= s.length()) { // sole opening quote
+      msg = "No closing quote [" + first_quote  + "]";
+      ok = false;
+    }
+    else {
+      while (ok && (index < s.length()-1)) {
+        char c = s.charAt(index);
+        if (esc) esc = false;
+        else {
+          if (c  == first_quote) {
+            msg = "Premature closing quote [" + first_quote  + "]";
+            ok = false;
+          }
+          else if (c  == '\\') esc = true;
+        }
+        index += 1;
+      }
+      if (ok && (esc || (s.charAt(index) != first_quote))) {
+        msg = "Missing closing quote [" + first_quote  + "]";
+        ok = false;
+      }
+    }
+    //
+    if (! ok) {
+        getHolder().createErrorAnnotation(node, msg);
+    }
+  }
+}