+// Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
package org.xwt.js;
+
+// FIXME: line number accuracy
+
import org.xwt.util.*;
import java.io.*;
-// FIXME: for..in
-// FIXME: delete keyword
-public class Parser extends Lexer {
+/**
+ * Parses a stream of lexed tokens into a tree of CompiledFunction's.
+ *
- public Parser(Reader r) throws IOException { super(r); }
- private Parser skipToken() throws IOException { getToken(); return this; }
-
- /** sorta like gcc trees */
- public static class Expr {
- int code = -1;
+ * There are three kinds of things we parse: blocks, statements,
+ * expressions. Expressions are a special type of statement that
+ * evaluates to a value (for example, "break" is not an expression,
+ * but "3+2" is). AssignmentTargets are a special kind of expression
+ * that can be 'put' to (for example, "foo()" is not an
+ * assignmentTarget, but "foo[7]" is). FIXME.
+
+ *
+ * Technically it would be a better design for this class to build an
+ * intermediate parse tree and use that to emit bytecode. Here's the
+ * tradeoff:
+ *
+ * Advantages of building a parse tree:
+ * - easier to apply optimizations
+ * - would let us handle more sophisticated languages than JavaScript
+ *
+ * Advantages of leaving out the parse tree
+ * - faster compilation
+ * - less load on the garbage collector
+ * - much simpler code, easier to understand
+ * - less error-prone
+ *
+ * Fortunately JS is such a simple language that we can get away with
+ * the half-assed approach and still produce a working, complete
+ * compiler.
+ *
+ * The bytecode language emitted doesn't really cause any appreciable
+ * semantic loss, and is itself a parseable language very similar to
+ * Forth or a postfix variant of LISP. This means that the bytecode
+ * can be transformed into a parse tree, which can be manipulated.
+ * So if we ever want to add an optimizer, it could easily be done by
+ * producing a parse tree from the bytecode, optimizing that tree,
+ * and then re-emitting the bytecode. The parse tree node class
+ * would also be much simpler since the bytecode language has so few
+ * operators.
+ *
+ * Actually, the above paragraph is slightly inaccurate -- there are
+ * places where we push a value and then perform an arbitrary number
+ * of operations using it before popping it; this doesn't parse well.
+ * But these cases are clearly marked and easy to change if we do
+ * need to move to a parse tree format.
+ */
+class Parser extends Lexer implements ByteCodes {
- Expr left = null;
- Expr right = null;
- Expr extra = null;
- Expr next = null; // if this expr is part of a list
+ // Constructors //////////////////////////////////////////////////////
- String string = null;
+ public Parser(Reader r, String sourceName, int line) throws IOException { super(r, sourceName, line); }
- public Expr(String s) { this.string = s; } // an identifier or label
- public Expr(int code) { this(code, null, null, null); }
- public Expr(int code, Expr left) { this(code, left, null, null); }
- public Expr(int code, Expr left, Expr right) { this(code, left, right, null); }
- public Expr(int code, Expr left, Expr right, Expr extra) { this.left = left; this.right = right; this.extra = extra; this.code = code; }
+ /** for debugging */
+ public static void main(String[] s) throws Exception {
+ CompiledFunction block = new CompiledFunction("stdin", 0, new InputStreamReader(System.in), null);
+ if (block == null) return;
+ System.out.println(block);
}
-
- /** parses a single statement */
- public Expr parseStatement() throws IOException {
- int tok;
- Expr ret;
- switch(tok = peekToken()) {
-
- case LC:
- ret = parseBlock(true);
-
- case THROW: case RETURN: case ASSERT:
- ret = new Expr(ASSERT, skipToken().parseExpr());
-
- case GOTO: case BREAK: case CONTINUE:
- skipToken();
- if (getToken() == NAME)
- ret = new Expr(tok, new Expr(string));
- else if (tok == GOTO)
- throw new Error("goto must be followed by a label");
- else
- ret = new Expr(tok);
-
- default:
- ret = parseExpr();
- }
-
- if (getToken() != SEMI) throw new Error("expected ;");
- return ret;
+
+
+ // Statics ////////////////////////////////////////////////////////////
+
+ static byte[] precedence = new byte[MAX_TOKEN + 1];
+ static boolean[] isRightAssociative = new boolean[MAX_TOKEN + 1];
+ static {
+ isRightAssociative[ASSIGN] = true;
+
+ precedence[ASSIGN] = 1;
+ precedence[HOOK] = 2;
+ precedence[COMMA] = 3;
+ precedence[OR] = precedence[AND] = 4;
+ precedence[GT] = precedence[GE] = 5;
+ precedence[BITOR] = 6;
+ precedence[BITXOR] = 7;
+ precedence[BITAND] = 8;
+ precedence[EQ] = precedence[NE] = 9;
+ precedence[LT] = precedence[LE] = 10;
+ precedence[SHEQ] = precedence[SHNE] = 11;
+ precedence[LSH] = precedence[RSH] = precedence[URSH] = 12;
+ precedence[ADD] = precedence[SUB] = 13;
+ precedence[MUL] = precedence[DIV] = precedence[MOD] = 14;
+ precedence[BITNOT] = 15;
+ precedence[INC] = precedence[DEC] = 16;
+ precedence[LP] = 17;
+ precedence[LB] = 18;
+ precedence[DOT] = 19;
}
- /** a block is either a single statement or a list of statements surrounded by curly braces; all expressions are also statements */
- public Expr parseBlock(boolean requireBraces) throws IOException {
- int tok = peekToken();
- if (requireBraces && tok != LC) throw new Error("expected {");
- if (tok != LC) return parseStatement();
- skipToken();
- Expr head = null;
- Expr tail = null;
- while(peekToken() != RC)
- if (head == null) head = tail = parseStatement(); else tail = tail.next = parseStatement();
- skipToken();
- return new Expr(LC, head);
+
+ // Parsing Logic /////////////////////////////////////////////////////////
+
+ /** gets a token and throws an exception if it is not <tt>code</tt> */
+ private void consume(int code) throws IOException {
+ if (getToken() != code) throw new ParserException("expected " + codeToString[code] + ", got " + (op == -1 ? "EOF" : codeToString[op]));
}
- /** Subexpressions come in two flavors: starters and continuers.
- * Starters can appear at the start of an expression or after a
- * continuer, and continuers, which can appear after a starter.
+ /**
+ * Parse the largest possible expression containing no operators
+ * of precedence below <tt>minPrecedence</tt> and append the
+ * bytecodes for that expression to <tt>appendTo</tt>; the
+ * appended bytecodes MUST grow the stack by exactly one element.
*/
- public Expr parseExpr() throws IOException {
- Expr e = parseStarter();
- while(true) {
- Expr e2 = parseContinuer(e);
- if (e2 == null) return e;
- e = e2;
+ private void startExpr(CompiledFunction appendTo, int minPrecedence) throws IOException {
+ int tok = getToken();
+ CompiledFunction b = appendTo;
+
+ switch (tok) {
+ case -1: throw new ParserException("expected expression");
+
+ // all of these simply push values onto the stack
+ case NUMBER: b.add(line, LITERAL, number); break;
+ case STRING: b.add(line, LITERAL, string); break;
+ case THIS: b.add(line, TOPSCOPE, null); break;
+ case NULL: b.add(line, LITERAL, null); break;
+ case TRUE: case FALSE: b.add(line, LITERAL, new Boolean(tok == TRUE)); break;
+
+ case LB: {
+ b.add(line, ARRAY, new Integer(0)); // push an array onto the stack
+ int size0 = b.size();
+ int i = 0;
+ if (peekToken() != RB)
+ while(true) { // iterate over the initialization values
+ int size = b.size();
+ if (peekToken() == COMMA || peekToken() == RB)
+ b.add(line, LITERAL, null); // for stuff like [1,,2,]
+ else
+ startExpr(b, -1); // push the value onto the stack
+ b.add(line, LITERAL, new Integer(i++)); // push the index in the array to place it into
+ b.add(line, PUT); // put it into the array
+ b.add(line, POP); // discard the value remaining on the stack
+ if (peekToken() == RB) break;
+ consume(COMMA);
+ }
+ b.set(size0 - 1, new Integer(i)); // back at the ARRAY instruction, write the size of the array
+ consume(RB);
+ break;
+ }
+ case SUB: { // negative literal (like "3 * -1")
+ consume(NUMBER);
+ b.add(line, LITERAL, new Double(number.doubleValue() * -1));
+ break;
+ }
+ case LP: { // grouping (not calling)
+ startExpr(b, -1);
+ consume(RP);
+ break;
+ }
+ case INC: case DEC: { // prefix (not postfix)
+ startExpr(b, precedence[tok]);
+ b.set(b.size() - 1, tok, new Boolean(true)); // FIXME, ugly; need startAssignTarget
+ break;
+ }
+ case BANG: case BITNOT: case TYPEOF: {
+ startExpr(b, precedence[tok]);
+ b.add(line, tok);
+ break;
+ }
+ case LC: { // object constructor
+ b.add(line, OBJECT, null); // put an object on the stack
+ if (peekToken() != RC)
+ while(true) {
+ if (peekToken() != NAME && peekToken() != STRING)
+ throw new ParserException("expected NAME or STRING");
+ getToken();
+ b.add(line, LITERAL, string); // grab the key
+ consume(COLON);
+ startExpr(b, -1); // grab the value
+ b.add(line, PUT); // put the value into the object
+ b.add(line, POP); // discard the remaining value
+ if (peekToken() == RC) break;
+ consume(COMMA);
+ if (peekToken() == RC) break; // we permit {,,} -- I'm not sure if ECMA does
+ }
+ consume(RC);
+ break;
+ }
+ case NAME: { // FIXME; this is an lvalue
+ String name = string;
+ if (peekToken() == ASSIGN) {
+ consume(ASSIGN);
+ b.add(line, TOPSCOPE);
+ b.add(line, LITERAL, name);
+ startExpr(b, minPrecedence);
+ b.add(line, PUT);
+ b.add(line, SWAP);
+ b.add(line, POP);
+ } else {
+ b.add(line, TOPSCOPE);
+ b.add(line, LITERAL, name);
+ b.add(line, GET);
+ }
+ break;
}
+ case FUNCTION: {
+ consume(LP);
+ int numArgs = 0;
+ CompiledFunction b2 = new CompiledFunction(sourceName, line, null);
+ b.add(line, NEWFUNCTION, b2);
+
+ // function prelude; arguments array is already on the stack
+ b2.add(line, TOPSCOPE); // push the scope onto the stack
+ b2.add(line, SWAP); // swap 'this' and 'arguments'
+
+ b2.add(line, LITERAL, "arguments"); // declare arguments (equivalent to 'var arguments;')
+ b2.add(line, DECLARE);
+
+ b2.add(line, LITERAL, "arguments"); // set this.arguments and leave the value on the stack
+ b2.add(line, SWAP);
+ b2.add(line, PUT);
+ b2.add(line, SWAP);
+ b2.add(line, POP);
+
+ while(peekToken() != RP) { // run through the list of argument names
+ if (peekToken() == NAME) {
+ consume(NAME); // a named argument
+
+ b2.add(line, LITERAL, string); // declare the name
+ b2.add(line, DECLARE);
+
+ b2.add(line, LITERAL, new Integer(numArgs)); // retrieve it from the arguments array
+ b2.add(line, GET_PRESERVE);
+ b2.add(line, SWAP);
+ b2.add(line, POP);
+
+ b2.add(line, TOPSCOPE); // put it to the current scope
+ b2.add(line, SWAP);
+ b2.add(line, LITERAL, string);
+ b2.add(line, SWAP);
+ b2.add(line, PUT);
+
+ b2.add(line, POP); // clean the stack
+ b2.add(line, POP);
+ }
+ if (peekToken() == RP) break;
+ consume(COMMA);
+ numArgs++;
+ }
+ consume(RP);
+
+ b2.add(line, POP); // pop off the arguments array
+
+ parseStatement(b2, null); // the function body
+
+ b2.add(line, LITERAL, null); // in case we "fall out the bottom", return NULL
+ b2.add(line, RETURN);
+
+ break;
+ }
+ default: throw new ParserException("expected expression, found " + codeToString[tok] + ", which cannot start an expression");
+ }
+
+ // attempt to continue the expression
+ continueExpr(b, minPrecedence);
}
- public Expr parseStarter() throws IOException {
- Expr e1 = null;
- Expr e2 = null;
- Expr e3 = null;
- Expr head = null;
- Expr tail = null;
+ /**
+ * Assuming that a complete expression has just been parsed,
+ * <tt>continueExpr</tt> will attempt to extend this expression by
+ * parsing additional tokens and appending additional bytecodes.
+ *
+ * No operators with precedence less than <tt>minPrecedence</tt>
+ * will be parsed.
+ *
+ * If any bytecodes are appended, they will not alter the stack
+ * depth.
+ */
+ private void continueExpr(CompiledFunction b, int minPrecedence) throws IOException {
+ if (b == null) throw new Error("got null b; this should never happen");
int tok = getToken();
- switch(tok) {
-
- case SWITCH: {
- if (getToken() != LP) throw new Error("expected left paren");
- Expr switchExpr = parseExpr();
- if (getToken() != RP) throw new Error("expected left paren");
- if (getToken() != LC) throw new Error("expected left brace");
- Expr firstExpr = null;
- Expr lastExpr = null;
- while(true) {
- if (getToken() != CASE) throw new Error("expected CASE");
- Expr caseExpr = parseExpr();
- if (getToken() != COLON) throw new Error("expected COLON");
- Expr e = new Expr(CASE, caseExpr, parseBlock(false));
- if (lastExpr == null) firstExpr = e;
- else lastExpr.next = e;
- lastExpr = e;
- if (getToken() == RC) return new Expr(SWITCH, switchExpr, firstExpr);
+ if (tok == -1) return;
+ if (minPrecedence != -1 && (precedence[tok] < minPrecedence || (precedence[tok] == minPrecedence && !isRightAssociative[tok]))) {
+ pushBackToken();
+ return;
+ }
+
+ switch (tok) {
+ case ASSIGN_BITOR: case ASSIGN_BITXOR: case ASSIGN_BITAND: case ASSIGN_LSH: case ASSIGN_RSH: case ASSIGN_URSH:
+ case ASSIGN_ADD: case ASSIGN_SUB: case ASSIGN_MUL: case ASSIGN_DIV: case ASSIGN_MOD: {
+ b.set(b.size() - 1, b.GET_PRESERVE, new Boolean(true)); // FIXME should use AssignTarget
+ startExpr(b, precedence[tok - 1]);
+ b.add(line, tok - 1);
+ b.add(line, PUT);
+ b.add(line, SWAP);
+ b.add(line, POP);
+ break;
+ }
+ case INC: case DEC: { // postfix
+ b.set(b.size() - 1, tok, new Boolean(false)); // FIXME use assignmenttarget
+ break;
+ }
+ case LP: { // invocation (not grouping)
+ int i = 0;
+ while(peekToken() != RP) {
+ i++;
+ if (peekToken() != COMMA) {
+ startExpr(b, -1);
+ if (peekToken() == RP) break;
+ }
+ consume(COMMA);
}
+ consume(RP);
+ b.add(line, CALL, new Integer(i));
+ break;
}
-
- case FUNCTION: {
- if (getToken() != LP) throw new Error("function keyword must be followed by a left paren");
- Expr formalArgs = null, cur = null;
- tok = getToken();
- while(tok != RP) {
- if (tok != NAME) throw new Error("expected a variable name");
- if (cur == null) { formalArgs = cur = new Expr(string); }
- else { cur.next = new Expr(string); cur = cur.next; }
- tok = getToken();
- if (tok == RP) break;
- if (tok != COMMA) throw new Error("function argument list must consist of alternating NAMEs and COMMAs");
- tok = getToken();
+ case BITOR: case BITXOR: case BITAND: case SHEQ: case SHNE: case LSH:
+ case RSH: case URSH: case ADD: case MUL: case DIV: case MOD:
+ case GT: case GE: case EQ: case NE: case LT: case LE: case SUB: {
+ startExpr(b, precedence[tok]);
+ b.add(line, tok);
+ break;
+ }
+ case OR: case AND: {
+ b.add(line, tok == AND ? b.JF : b.JT, new Integer(0)); // test to see if we can short-circuit
+ int size = b.size();
+ startExpr(b, precedence[tok]); // otherwise check the second value
+ b.add(line, JMP, new Integer(2)); // leave the second value on the stack and jump to the end
+ b.add(line, LITERAL, tok == AND ? new Boolean(false) : new Boolean(true)); // target of the short-circuit jump is here
+ b.set(size - 1, new Integer(b.size() - size)); // write the target of the short-circuit jump
+ break;
+ }
+ case DOT: { // FIXME, assigntarget
+ consume(NAME);
+ String target = string;
+ if (peekToken() == ASSIGN) {
+ consume(ASSIGN);
+ b.add(line, LITERAL, target);
+ startExpr(b, -1);
+ b.add(line, PUT);
+ b.add(line, SWAP);
+ b.add(line, POP);
+ } else {
+ b.add(line, LITERAL, target);
+ b.add(line, GET);
+ }
+ break;
+ }
+ case LB: { // subscripting (not array constructor)
+ startExpr(b, -1);
+ consume(RB);
+ if (peekToken() == ASSIGN) { // FIXME: assigntarget
+ consume(ASSIGN);
+ startExpr(b, -1);
+ b.add(line, PUT);
+ b.add(line, SWAP);
+ b.add(line, POP);
+ } else {
+ b.add(line, GET);
}
- return new Expr(tok, formalArgs, parseBlock(true));
+ break;
+ }
+ case HOOK: {
+ b.add(line, JF, new Integer(0)); // jump to the if-false expression
+ int size = b.size();
+ startExpr(b, -1); // write the if-true expression
+ b.add(line, JMP, new Integer(0)); // if true, jump *over* the if-false expression
+ b.set(size - 1, new Integer(b.size() - size + 1)); // now we know where the target of the jump is
+ consume(COLON);
+ size = b.size();
+ startExpr(b, -1); // write the if-false expression
+ b.set(size - 1, new Integer(b.size() - size + 1)); // this is the end; jump to here
+ break;
+ }
+ default: {
+ pushBackToken();
+ return;
+ }
+ }
+
+ continueExpr(b, minPrecedence); // try to continue the expression
+ }
+
+ /** Parse a block of statements which must be surrounded by LC..RC. */
+ void parseBlock(CompiledFunction b) throws IOException { parseBlock(b, null); }
+ void parseBlock(CompiledFunction b, String label) throws IOException {
+ if (peekToken() == -1) return;
+ else if (peekToken() != LC) parseStatement(b, null);
+ else {
+ consume(LC);
+ while(peekToken() != RC && peekToken() != -1) parseStatement(b, null);
+ consume(RC);
+ }
+ }
+
+ /** Parse a single statement, consuming the RC or SEMI which terminates it. */
+ void parseStatement(CompiledFunction b, String label) throws IOException {
+ int tok = peekToken();
+ if (tok == -1) return;
+ switch(tok = getToken()) {
+
+ case THROW: case ASSERT: case RETURN: {
+ if (tok == RETURN && peekToken() == SEMI) b.add(line, LITERAL, null);
+ else startExpr(b, -1);
+ b.add(line, tok);
+ consume(SEMI);
+ break;
+ }
+
+ case BREAK: case CONTINUE: {
+ if (peekToken() == NAME) consume(NAME);
+ b.add(line, tok, string);
+ consume(SEMI);
+ break;
}
- case VAR:
+ case VAR: {
+ b.add(line, TOPSCOPE); // push the current scope
while(true) {
- if (getToken() != NAME) throw new Error("variable declarations must start with a variable name");
- Expr name = new Expr(string);
- Expr initVal = null;
- tok = peekToken();
- if (tok == ASSIGN) {
- skipToken();
- initVal = parseExpr();
- tok = peekToken();
+ consume(NAME);
+ String name = string;
+ b.add(line, LITERAL, name); // push the name to be declared
+ b.add(line, DECLARE); // declare it
+ if (peekToken() == ASSIGN) { // if there is an '=' after the variable name
+ b.add(line, LITERAL, name); // put the var name back on the stack
+ consume(ASSIGN);
+ startExpr(b, -1);
+ b.add(line, PUT);
+ b.add(line, POP);
}
- Expr e = new Expr(VAR, name, initVal);
- if (head == null) head = tail = e; else tail = tail.next = e;
- if (tok != COMMA) break;
- skipToken();
+ if (peekToken() != COMMA) break;
+ consume(COMMA);
}
- return new Expr(VAR, head);
+ b.add(line, POP);
+ if ((mostRecentlyReadToken != RC || peekToken() == SEMI) && peekToken() != -1) consume(SEMI);
+ break;
+ }
- case LC:
- tok = getToken();
- while(true) {
- if (tok == RP) return new Expr(LC, head);
- if (tok != NAME) throw new Error("expecting name");
- Expr name = parseExpr();
- if (tok != COLON) throw new Error("expecting colon");
- e1 = new Expr(COLON, name, parseExpr());
- if (head == null) head = tail = e1; else tail = tail.next = e1;
- tok = getToken();
- if (tok != COMMA && tok != RP) throw new Error("expected right curly or comma");
- }
+ case IF: {
+ consume(LP);
+ startExpr(b, -1);
+ consume(RP);
- case LB:
- tok = getToken();
- while(true) {
- if (tok == RB) return new Expr(LB, head);
- if (head == null) head = tail = parseExpr(); else tail = tail.next = parseExpr();
- tok = getToken();
- if (tok != COMMA && tok != RP) throw new Error("expected right bracket or comma");
+ b.add(line, JF, new Integer(0));
+ int size = b.size();
+ parseStatement(b, null);
+
+ if (peekToken() == ELSE) {
+ consume(ELSE);
+ b.set(size - 1, new Integer(2 + b.size() - size));
+ b.add(line, JMP, new Integer(0));
+ size = b.size();
+ parseStatement(b, null);
}
+ b.set(size - 1, new Integer(1 + b.size() - size));
+ break;
+ }
- case NAME:
- return new Expr(string);
-
- case INC: case DEC: case TYPEOF:
- return new Expr(tok, parseExpr());
+ case WHILE: {
+ consume(LP);
+ if (label != null) b.add(line, LABEL, label);
+ b.add(line, LOOP);
+ int size = b.size();
+ b.add(line, POP);
+ startExpr(b, -1);
+ b.add(line, JT, new Integer(2));
+ b.add(line, BREAK);
+ consume(RP);
+ parseStatement(b, null);
+ b.add(line, CONTINUE); // if we fall out of the end, definately continue
+ b.set(size - 1, new Integer(b.size() - size + 1)); // end of the loop
+ break;
+ }
+
+ case SWITCH: {
+ consume(LP);
+ if (label != null) b.add(line, LABEL, label);
+ b.add(line, LOOP);
+ int size0 = b.size();
+ startExpr(b, -1);
+ consume(RP);
+ consume(LC);
+ while(true)
+ if (peekToken() == CASE) {
+ consume(CASE);
+ b.add(line, DUP);
+ startExpr(b, -1);
+ consume(COLON);
+ b.add(line, EQ);
+ b.add(line, JF, new Integer(0));
+ int size = b.size();
+ while(peekToken() != CASE && peekToken() != DEFAULT && peekToken() != RC) {
+ int size2 = b.size();
+ parseStatement(b, null);
+ if (size2 == b.size()) break;
+ }
+ b.set(size - 1, new Integer(1 + b.size() - size));
+ } else if (peekToken() == DEFAULT) {
+ consume(DEFAULT);
+ consume(COLON);
+ while(peekToken() != CASE && peekToken() != DEFAULT && peekToken() != RC) {
+ int size2 = b.size();
+ parseStatement(b, null);
+ if (size2 == b.size()) break;
+ }
+ } else if (peekToken() == RC) {
+ consume(RC);
+ b.add(line, BREAK);
+ break;
+ } else {
+ throw new ParserException("expected CASE, DEFAULT, or RC; got " + codeToString[peekToken()]);
+ }
+ b.add(line, BREAK);
+ b.set(size0 - 1, new Integer(b.size() - size0 + 1)); // end of the loop
+ break;
+ }
- case TRUE: case FALSE: case NOP:
- return new Expr(tok);
+ case DO: {
+ if (label != null) b.add(line, LABEL, label);
+ b.add(line, LOOP);
+ int size = b.size();
+ parseStatement(b, null);
+ consume(WHILE);
+ consume(LP);
+ startExpr(b, -1);
+ b.add(line, JT, new Integer(2));
+ b.add(line, BREAK);
+ b.add(line, CONTINUE);
+ consume(RP);
+ consume(SEMI);
+ b.set(size - 1, new Integer(b.size() - size + 1)); // end of the loop
+ break;
+ }
case TRY: {
- // FIXME: we deliberately allow you to omit braces in catch{}/finally{} if they are single statements...
- Expr tryBlock = parseBlock(true);
- while ((tok = peekToken()) == CATCH)
- if (head == null) head = tail = parseBlock(false); else tail = tail.next = parseBlock(false);
- if (head == null) throw new Error("try without catch");
- return new Expr(TRY, tryBlock, head, tok == FINALLY ? skipToken().parseBlock(false) : null);
- }
+ // We deliberately allow you to omit braces in catch{}/finally{} if they are single statements...
+ b.add(line, TRY);
+ int size = b.size();
+ parseBlock(b, null);
+ b.add(line, POP); // pop the TryMarker
+ b.add(line, JMP); // jump forward to the end of the catch block
+ int size2 = b.size();
+ b.set(size - 1, new Integer(b.size() - size + 1));// the TRY argument points at the start of the CATCH block
- case IF: case WHILE: {
- if (getToken() != LP) throw new Error("expected left paren");
- Expr parenExpr = parseExpr();
- if (getToken() != RP) throw new Error("expected right paren");
- Expr firstBlock = parseBlock(false);
- if (tok == IF && peekToken() == ELSE) return new Expr(tok, parenExpr, firstBlock, skipToken().parseBlock(false));
- return new Expr(tok, parenExpr, firstBlock);
- }
-
- case FOR:
- // FIXME: for..in
- if (getToken() != LP) throw new Error("expected left paren");
- e1 = parseStatement();
- e2 = parseStatement();
- e3 = parseStatement(); // FIXME: this guy has to be okay with ending via a )
- if (getToken() != RP) throw new Error("expected right paren");
- throw new Error("not yet implemented");
- //return new Expr(FOR, e1, e2, e3, parseBlock(false));
+ if (peekToken() == CATCH) {
+ getToken();
+ consume(LP);
+ consume(NAME);
+ consume(RP);
+ // FIXME, we need an extra scope here
+ b.add(line, TOPSCOPE); // the exception is on top of the stack; put it to the variable
+ b.add(line, SWAP);
+ b.add(line, LITERAL);
+ b.add(line, SWAP);
+ b.add(line, PUT);
+ b.add(line, POP);
+ b.add(line, POP);
+ parseStatement(b, null);
+ }
- case DO: {
- Expr firstBlock = parseBlock(false);
- if (getToken() != WHILE) throw new Error("expecting WHILE");
- if (getToken() != LP) throw new Error("expected left paren");
- Expr whileExpr = parseExpr();
- if (getToken() != RP) throw new Error("expected right paren");
- if (getToken() != SEMI) throw new Error("semicolon");
- return new Expr(DO, firstBlock, whileExpr);
+ b.set(size2 - 1, new Integer(b.size() - size2 + 1)); // jump here if no exception was thrown
+
+ // FIXME: not implemented correctly
+ if (peekToken() == FINALLY) {
+ consume(FINALLY);
+ parseStatement(b, null);
+ }
+ break;
}
- case VOID: case RESERVED:
- throw new Error("reserved word that you shouldn't be using");
-
- case WITH:
- throw new Error("WITH not yet implemented"); // FIXME
-
- default: throw new Error("I wasn't expecting a " + tok);
+ case FOR: {
+ consume(LP);
+
+ tok = getToken();
+ boolean hadVar = false;
+ if (tok == VAR) { hadVar = true; tok = getToken(); }
+ String varName = string;
+ boolean forIn = peekToken() == IN;
+ pushBackToken(tok, varName);
+
+ if (forIn) {
+ // FIXME: break needs to work in here
+ consume(NAME);
+ consume(IN);
+ startExpr(b, -1);
+ b.add(line, PUSHKEYS);
+ b.add(line, LITERAL, "length");
+ b.add(line, GET);
+ consume(RP);
+ CompiledFunction b2 = new CompiledFunction(sourceName, line, null);
+
+ b.add(line, NEWSCOPE);
+
+ b.add(line, LITERAL, new Integer(1));
+ b.add(line, SUB);
+ b.add(line, DUP);
+ b.add(line, LITERAL, new Integer(0));
+ b.add(line, LT);
+ b.add(line, JT, new Integer(7));
+ b.add(line, GET_PRESERVE);
+ b.add(line, LITERAL, varName);
+ b.add(line, LITERAL, varName);
+ b.add(line, DECLARE);
+ b.add(line, PUT);
+ parseStatement(b, null);
+
+ b.add(line, OLDSCOPE);
+
+ break;
+
+ } else {
+ if (hadVar) pushBackToken(VAR, null);
+ b.add(line, NEWSCOPE);
+
+ parseStatement(b, null);
+ CompiledFunction e2 = new CompiledFunction(sourceName, line, null);
+ if (peekToken() != SEMI) {
+ startExpr(e2, -1);
+ } else {
+ e2.add(line, b.LITERAL, Boolean.TRUE);
+ }
+ consume(SEMI);
+ if (label != null) b.add(line, LABEL, label);
+ b.add(line, LOOP);
+ int size2 = b.size();
+
+ b.add(line, JT, new Integer(0));
+ int size = b.size();
+ if (peekToken() != RP) {
+ startExpr(b, -1);
+ b.add(line, POP);
+ }
+ b.set(size - 1, new Integer(b.size() - size + 1));
+ consume(RP);
+
+ b.paste(e2);
+ b.add(line, JT, new Integer(2));
+ b.add(line, BREAK);
+ parseStatement(b, null);
+ b.add(line, CONTINUE);
+ b.set(size2 - 1, new Integer(b.size() - size2 + 1)); // end of the loop
+
+ b.add(line, OLDSCOPE);
+ break;
+ }
}
- }
-
- // called after each parseExpr(); returns null if we can't make the expression any bigger
- public Expr parseContinuer(Expr prefix) throws IOException {
- Expr head = null;
- Expr tail = null;
- Expr e1, e2, e3;
- Expr ret = null;
- int tok;
-
- // FIXME: postfix and infix operators -- need to handle precedence
- switch (tok = getToken()) {
-
- case BITOR: case BITXOR: case BITAND: case EQ: case NE: case LT: case LE:
- case GT: case GE: case LSH: case RSH: case URSH: case ADD: case SUB: case MUL:
- case DIV: case MOD: case BITNOT: case SHEQ: case SHNE: case INSTANCEOF:
- case OR: case AND: case COMMA: case INC: case DEC:
- throw new Error("haven't figured out how to handle postfix/infix operators yet");
- //return new Expr(tok, prefix, (tok == INC || tok == DEC) ? null : parseExpr());
-
- case ASSIGN:
- throw new Error("haven't figured out how to handle postfix/infix operators yet");
-
- case LP:
- while(peekToken() != RP) {
- if (head == null) head = tail = parseExpr(); else tail = tail.next = parseExpr();
- tok = getToken();
- if (tok == RP) break;
- if (tok != COMMA) throw new Error("expected comma or right paren");
+
+ case NAME: {
+ String possiblyTheLabel = string;
+ if (peekToken() == COLON) {
+ consume(COLON);
+ label = possiblyTheLabel;
+ parseStatement(b, label);
+ break;
+ } else {
+ pushBackToken(NAME, possiblyTheLabel);
+ startExpr(b, -1);
+ b.add(line, POP);
+ if ((mostRecentlyReadToken != RC || peekToken() == SEMI) && peekToken() != -1) consume(SEMI);
+ break;
}
- return new Expr(LP, prefix, head);
+ }
- case LB:
- e1 = parseExpr();
- if (getToken() != RB) throw new Error("expected a right brace");
- return new Expr(LB, prefix, e1);
-
- case HOOK:
- e2 = parseExpr();
- if (getToken() != COLON) throw new Error("expected colon to close ?: expression");
- e3 = parseExpr();
- return new Expr(HOOK, prefix, e2, e3);
-
- default:
+ case SEMI: return;
+ case LC: {
pushBackToken();
- return null;
+ parseBlock(b, label);
+ break;
+ }
+
+ default: {
+ pushBackToken();
+ startExpr(b, -1);
+ b.add(line, POP);
+ if ((mostRecentlyReadToken != RC || peekToken() == SEMI) && peekToken() != -1) consume(SEMI);
+ break;
+ }
}
}
+
+
+ // ParserException //////////////////////////////////////////////////////////////////////
+
+ private class ParserException extends IOException { public ParserException(String s) { super(sourceName + ":" + line + " " + s); } }
}
projects / org.ibex.core.git / blobdiff