parser.java

這是一個javascript 的 interpreter是了解 web browser的好材料

                        mustMatchToken(Token.COLON, "msg.no.colon.case");
                        decompiler.addEOL(Token.COLON);
                        break;

                      default:
                        reportError("msg.bad.switch");
                        break switchLoop;
                    }

                    Node block = nf.createLeaf(Token.BLOCK);
                    while ((tt = peekToken()) != Token.RC
                           && tt != Token.CASE
                           && tt != Token.DEFAULT
                           && tt != Token.EOF)
                    {
                        nf.addChildToBack(block, statement());
                    }

                    // caseExpression == null => add default label
                    nf.addSwitchCase(pn, caseExpression, block);
                }
                decompiler.addEOL(Token.RC);
                nf.closeSwitch(pn);
            } finally {
                exitSwitch();
            }
            return pn;
          }

          case Token.WHILE: {
            consumeToken();
            decompiler.addToken(Token.WHILE);

            Node loop = enterLoop(statementLabel, true);
            try {
                Node cond = condition();
                decompiler.addEOL(Token.LC);
                Node body = statement();
                decompiler.addEOL(Token.RC);
                pn = nf.createWhile(loop, cond, body);
            } finally {
                exitLoop(true);
            }
            return pn;
          }

          case Token.DO: {
            consumeToken();
            decompiler.addToken(Token.DO);
            decompiler.addEOL(Token.LC);

            Node loop = enterLoop(statementLabel, true);
            try {
                Node body = statement();
                decompiler.addToken(Token.RC);
                mustMatchToken(Token.WHILE, "msg.no.while.do");
                decompiler.addToken(Token.WHILE);
                Node cond = condition();
                pn = nf.createDoWhile(loop, body, cond);
            } finally {
                exitLoop(true);
            }
            // Always auto-insert semicolon to follow SpiderMonkey:
            // It is required by ECMAScript but is ignored by the rest of
            // world, see bug 238945
            matchToken(Token.SEMI);
            decompiler.addEOL(Token.SEMI);
            return pn;
          }

          case Token.FOR: {
            consumeToken();
            boolean isForEach = false;
            decompiler.addToken(Token.FOR);

            Node loop = enterLoop(statementLabel, true);
            try {
                Node init;  // Node init is also foo in 'foo in object'
                Node cond;  // Node cond is also object in 'foo in object'
                Node incr = null;
                Node body;
                int declType = -1;

                // See if this is a for each () instead of just a for ()
                if (matchToken(Token.NAME)) {
                    decompiler.addName(ts.getString());
                    if (ts.getString().equals("each")) {
                        isForEach = true;
                    } else {
                        reportError("msg.no.paren.for");
                    }
                }

                mustMatchToken(Token.LP, "msg.no.paren.for");
                decompiler.addToken(Token.LP);
                tt = peekToken();
                if (tt == Token.SEMI) {
                    init = nf.createLeaf(Token.EMPTY);
                } else {
                    if (tt == Token.VAR || tt == Token.LET) {
                        // set init to a var list or initial
                        consumeToken();    // consume the token
                        decompiler.addToken(tt);
                        init = variables(true, tt);
                        declType = tt;
                    }
                    else {
                        init = expr(true);
                    }
                }

                if (matchToken(Token.IN)) {
                    decompiler.addToken(Token.IN);
                    // 'cond' is the object over which we're iterating
                    cond = expr(false);
                } else {  // ordinary for loop
                    mustMatchToken(Token.SEMI, "msg.no.semi.for");
                    decompiler.addToken(Token.SEMI);
                    if (peekToken() == Token.SEMI) {
                        // no loop condition
                        cond = nf.createLeaf(Token.EMPTY);
                    } else {
                        cond = expr(false);
                    }

                    mustMatchToken(Token.SEMI, "msg.no.semi.for.cond");
                    decompiler.addToken(Token.SEMI);
                    if (peekToken() == Token.RP) {
                        incr = nf.createLeaf(Token.EMPTY);
                    } else {
                        incr = expr(false);
                    }
                }

                mustMatchToken(Token.RP, "msg.no.paren.for.ctrl");
                decompiler.addToken(Token.RP);
                decompiler.addEOL(Token.LC);
                body = statement();
                decompiler.addEOL(Token.RC);

                if (incr == null) {
                    // cond could be null if 'in obj' got eaten
                    // by the init node.
                    pn = nf.createForIn(declType, loop, init, cond, body,
                                        isForEach);
                } else {
                    pn = nf.createFor(loop, init, cond, incr, body);
                }
            } finally {
                exitLoop(true);
            }
            return pn;
          }

          case Token.TRY: {
            consumeToken();
            int lineno = ts.getLineno();

            Node tryblock;
            Node catchblocks = null;
            Node finallyblock = null;

            decompiler.addToken(Token.TRY);
            if (peekToken() != Token.LC) {
                reportError("msg.no.brace.try");
            }
            decompiler.addEOL(Token.LC);
            tryblock = statement();
            decompiler.addEOL(Token.RC);

            catchblocks = nf.createLeaf(Token.BLOCK);

            boolean sawDefaultCatch = false;
            int peek = peekToken();
            if (peek == Token.CATCH) {
                while (matchToken(Token.CATCH)) {
                    if (sawDefaultCatch) {
                        reportError("msg.catch.unreachable");
                    }
                    decompiler.addToken(Token.CATCH);
                    mustMatchToken(Token.LP, "msg.no.paren.catch");
                    decompiler.addToken(Token.LP);

                    mustMatchToken(Token.NAME, "msg.bad.catchcond");
                    String varName = ts.getString();
                    decompiler.addName(varName);

                    Node catchCond = null;
                    if (matchToken(Token.IF)) {
                        decompiler.addToken(Token.IF);
                        catchCond = expr(false);
                    } else {
                        sawDefaultCatch = true;
                    }

                    mustMatchToken(Token.RP, "msg.bad.catchcond");
                    decompiler.addToken(Token.RP);
                    mustMatchToken(Token.LC, "msg.no.brace.catchblock");
                    decompiler.addEOL(Token.LC);

                    nf.addChildToBack(catchblocks,
                        nf.createCatch(varName, catchCond,
                                       statements(null),
                                       ts.getLineno()));

                    mustMatchToken(Token.RC, "msg.no.brace.after.body");
                    decompiler.addEOL(Token.RC);
                }
            } else if (peek != Token.FINALLY) {
                mustMatchToken(Token.FINALLY, "msg.try.no.catchfinally");
            }

            if (matchToken(Token.FINALLY)) {
                decompiler.addToken(Token.FINALLY);
                decompiler.addEOL(Token.LC);
                finallyblock = statement();
                decompiler.addEOL(Token.RC);
            }

            pn = nf.createTryCatchFinally(tryblock, catchblocks,
                                          finallyblock, lineno);

            return pn;
          }

          case Token.THROW: {
            consumeToken();
            if (peekTokenOrEOL() == Token.EOL) {
                // ECMAScript does not allow new lines before throw expression,
                // see bug 256617
                reportError("msg.bad.throw.eol");
            }

            int lineno = ts.getLineno();
            decompiler.addToken(Token.THROW);
            pn = nf.createThrow(expr(false), lineno);
            break;
          }

          case Token.BREAK: {
            consumeToken();
            int lineno = ts.getLineno();

            decompiler.addToken(Token.BREAK);

            // matchJumpLabelName only matches if there is one
            Node breakStatement = matchJumpLabelName();
            if (breakStatement == null) {
                if (loopAndSwitchSet == null || loopAndSwitchSet.size() == 0) {
                    reportError("msg.bad.break");
                    return null;
                }
                breakStatement = (Node)loopAndSwitchSet.peek();
            }
            pn = nf.createBreak(breakStatement, lineno);
            break;
          }

          case Token.CONTINUE: {
            consumeToken();
            int lineno = ts.getLineno();

            decompiler.addToken(Token.CONTINUE);

            Node loop;
            // matchJumpLabelName only matches if there is one
            Node label = matchJumpLabelName();
            if (label == null) {
                if (loopSet == null || loopSet.size() == 0) {
                    reportError("msg.continue.outside");
                    return null;
                }
                loop = (Node)loopSet.peek();
            } else {
                loop = nf.getLabelLoop(label);
                if (loop == null) {
                    reportError("msg.continue.nonloop");
                    return null;
                }
            }
            pn = nf.createContinue(loop, lineno);
            break;
          }

          case Token.WITH: {
            consumeToken();

            decompiler.addToken(Token.WITH);
            int lineno = ts.getLineno();
            mustMatchToken(Token.LP, "msg.no.paren.with");
            decompiler.addToken(Token.LP);
            Node obj = expr(false);
            mustMatchToken(Token.RP, "msg.no.paren.after.with");
            decompiler.addToken(Token.RP);
            decompiler.addEOL(Token.LC);

            ++nestingOfWith;
            Node body;
            try {
                body = statement();
            } finally {
                --nestingOfWith;
            }

            decompiler.addEOL(Token.RC);

            pn = nf.createWith(obj, body, lineno);
            return pn;
          }

          case Token.CONST:
          case Token.VAR: {
            consumeToken();
            decompiler.addToken(tt);
            pn = variables(false, tt);
            break;
          }
          
          case Token.LET: {
            consumeToken();
            decompiler.addToken(Token.LET);
            if (peekToken() == Token.LP) {
                pn = let(true);
            } else {
                pn = variables(false, tt);
            }
            return pn;
          }

          case Token.RETURN: 
          case Token.YIELD: {
            pn = returnOrYield(tt, false);
            break;
          }

          case Token.DEBUGGER:
            consumeToken();
            decompiler.addToken(Token.DEBUGGER);
            pn = nf.createDebugger(ts.getLineno());
            break;

          case Token.LC:
            consumeToken();
            if (statementLabel != null) {
                decompiler.addToken(Token.LC);
            }
            Node scope = nf.createScopeNode(Token.BLOCK, ts.getLineno());
            pushScope(scope);
            try {
                statements(scope);
                mustMatchToken(Token.RC, "msg.no.brace.block");
                if (statementLabel != null) {
                    decompiler.addEOL(Token.RC);
                }
                return scope;
            } finally {
                popScope();
            }

          case Token.ERROR:
            // Fall thru, to have a node for error recovery to work on
          case Token.SEMI:
            consumeToken();
            pn = nf.createLeaf(Token.EMPTY);
            return pn;

          case Token.FUNCTION: {
            consumeToken();
            pn = function(FunctionNode.FUNCTION_EXPRESSION_STATEMENT);
            return pn;
          }

          case Token.DEFAULT :
            consumeToken();
            mustHaveXML();

            decompiler.addToken(Token.DEFAULT);
            int nsLine = ts.getLineno();

            if (!(matchToken(Token.NAME)
                  && ts.getString().equals("xml")))
            {
                reportError("msg.bad.namespace");
            }
            decompiler.addName(" xml");

            if (!(matchToken(Token.NAME)
                  && ts.getString().equals("namespace")))
            {
                reportError("msg.bad.namespace");
            }
            decompiler.addName(" namespace");

            if (!matchToken(Token.ASSIGN)) {
                reportError("msg.bad.namespace");
            }
            decompiler.addToken(Token.ASSIGN);