Bail out unclosed block (#25)

* Report unclosed block in parsing

* Fix tests

* Resolve comments and rebase onto chapter5

* Test `isEOF` after consume whitespaces

1 files changed, 13 insertions, 5 deletions

diff --git a/chapter04/src/main/java/com/seaofnodes/simple/Parser.java b/chapter04/src/main/java/com/seaofnodes/simple/Parser.java
index 147515f6..275a4ebd 100644
--- a/chapter04/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter04/src/main/java/com/seaofnodes/simple/Parser.java
@@ -52,7 +52,7 @@ public class Parser {
         try {
             _scope.define("$ctrl", new ProjNode(START, 0, "$ctrl").peephole());
             _scope.define("arg"  , new ProjNode(START, 1, "arg"  ).peephole());
-            return (ReturnNode) parseBlock();
+            return (ReturnNode) parseBlock(false);
         }
         finally {
             _scope.pop();
@@ -66,14 +66,22 @@ public class Parser {
      *     '{' statements '}'
      * </pre>
      */
-    private Node parseBlock() {
+    private Node parseBlock(boolean requireClosingBracket) {
         // Enter a new scope
         _scope.push();
         Node n = null;
-        while (!match("}") && !_lexer.isEOF()) {
+        do {
+            if (match("}")) {
+                if (requireClosingBracket) break;
+                else throw error("unexpected '}' token");
+            } else if (_lexer.isEOF()) {
+                if (requireClosingBracket) require("}");
+                else break;
+            }
+
             Node n0 = parseStatement();
             if (n0 != null) n = n0; // Allow null returns from eg showGraph
-        }
+        } while (true);
         // Exit scope
         _scope.pop();
         return n;
@@ -89,7 +97,7 @@ public class Parser {
     private Node parseStatement() {
         if (match("return")) return parseReturn();
         else if (match("int")) return parseDecl();
-        else if (match("{")) return parseBlock();
+        else if (match("{")) return parseBlock(true);
         else if (match("#showGraph")) return showGraph();
         else return parseExpressionStatement();
     }