-// Copyright 2002 Adam Megacz, see the COPYING file for licensing [GPL]
+// Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
package org.xwt.js;
import org.xwt.util.*;
import java.io.*;
-/** parses a stream of lexed tokens into a tree of Expr's */
-public class Parser extends Lexer {
+/** parses a stream of lexed tokens into ForthBlock's */
+public class Parser extends Lexer implements OpCodes {
// Constructors //////////////////////////////////////////////////////
- public Parser(Reader r) throws IOException { super(r); }
+ public Parser(Reader r, String sourceName, int line) throws IOException {
+ super(r);
+ this.sourceName = sourceName;
+ this.line = line;
+ }
+ /** for debugging */
public static void main(String[] s) throws Exception {
- Parser p = new Parser(new InputStreamReader(System.in));
+ Parser p = new Parser(new InputStreamReader(System.in), "stdin", 0);
while(true) {
- Expr block = p.parseBlock(false);
+ ForthBlock block = new ForthBlock(0, "stdin");
+ p.parseStatement(false, block);
if (block == null) return;
System.out.println(block);
if (p.peekToken() == -1) return;
// Statics ////////////////////////////////////////////////////////////
static byte[] precedence = new byte[MAX_TOKEN + 1];
+ static boolean[] isRightAssociative = new boolean[MAX_TOKEN + 1];
+ static boolean[] mustStartExpression = new boolean[MAX_TOKEN + 1];
+ static boolean[] cannotStartExpression = new boolean[MAX_TOKEN + 1];
static {
- precedence[COMMA] = 1;
- precedence[ASSIGN] = 2;
- precedence[GT] = precedence[GE] = 3;
+
+ mustStartExpression[VAR] = true;
+ mustStartExpression[IF] = true;
+ mustStartExpression[BANG] = true;
+ mustStartExpression[BITNOT] = true;
+ mustStartExpression[INSTANCEOF] = true;
+ mustStartExpression[TYPEOF] = true;
+ mustStartExpression[NUMBER] = true;
+ mustStartExpression[STRING] = true;
+ mustStartExpression[NULL] = true;
+ mustStartExpression[TRUE] = true;
+ mustStartExpression[FALSE] = true;
+ mustStartExpression[Tokens.FUNCTION] = true;
+ mustStartExpression[NAME] = true;
+ mustStartExpression[LC] = true;
+ mustStartExpression[THIS] = true;
+
+ cannotStartExpression[OR] = true;
+ cannotStartExpression[AND] = true;
+ cannotStartExpression[BITOR] = true;
+ cannotStartExpression[BITXOR] = true;
+ cannotStartExpression[BITAND] = true;
+ cannotStartExpression[SHEQ] = true;
+ cannotStartExpression[SHNE] = true;
+ cannotStartExpression[LSH] = true;
+ cannotStartExpression[RSH] = true;
+ cannotStartExpression[URSH] = true;
+ cannotStartExpression[ADD] = true;
+ cannotStartExpression[MUL] = true;
+ cannotStartExpression[DIV] = true;
+ cannotStartExpression[MOD] = true;
+ cannotStartExpression[GT] = true;
+ cannotStartExpression[GE] = true;
+ cannotStartExpression[EQ] = true;
+ cannotStartExpression[NE] = true;
+ cannotStartExpression[LT] = true;
+ cannotStartExpression[LE] = true;
+ cannotStartExpression[DOT] = true;
+ cannotStartExpression[HOOK] = true;
+ cannotStartExpression[ASSIGN_BITOR] = true;
+ cannotStartExpression[ASSIGN_BITXOR] = true;
+ cannotStartExpression[ASSIGN_BITAND] = true;
+ cannotStartExpression[ASSIGN_LSH] = true;
+ cannotStartExpression[ASSIGN_RSH] = true;
+ cannotStartExpression[ASSIGN_URSH] = true;
+ cannotStartExpression[ASSIGN_ADD] = true;
+ cannotStartExpression[ASSIGN_SUB] = true;
+ cannotStartExpression[ASSIGN_MUL] = true;
+ cannotStartExpression[ASSIGN_DIV] = true;
+ cannotStartExpression[ASSIGN_MOD] = true;
+
+ isRightAssociative[ASSIGN] = true;
+
+ precedence[ASSIGN] = 1;
+ precedence[HOOK] = 2;
+ precedence[COMMA] = 3;
precedence[OR] = precedence[AND] = 4;
- precedence[BITOR] = 5;
- precedence[BITXOR] = 6;
- precedence[BITAND] = 7;
- precedence[EQ] = precedence[NE] = 8;
- precedence[LT] = precedence[LE] = 9;
- precedence[SHEQ] = precedence[SHNE] = 10;
- precedence[LSH] = precedence[RSH] = precedence[URSH] = 11;
- precedence[ADD] = precedence[SUB] = 12;
- precedence[MUL] = precedence[DIV] = precedence[MOD] = 13;
- precedence[BITNOT] = precedence[INSTANCEOF] = 14;
- precedence[INC] = precedence[DEC] = 15;
- precedence[LP] = 16;
- precedence[DOT] = 17;
+ 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] = precedence[INSTANCEOF] = 15;
+ precedence[INC] = precedence[DEC] = 16;
+ precedence[LP] = 17;
+ precedence[LB] = 18;
+ precedence[DOT] = 19;
}
- // Useful Types /////////////////////////////////////////////////////////
-
- /** sorta like gcc trees */
- public static class Expr {
-
- int code = -1;
-
- Expr left = null;
- Expr right = null;
- Expr next = null; // if this expr is part of a list
+ // Parsing Logic /////////////////////////////////////////////////////////
- String string = null;
- Number number = null;
-
- public String toString() { return toString(0); }
- public String toString(int indent) {
- String ret = "";
- for(int i=0; i<indent; i++) ret += " ";
- ret += codeToString[code];
- if (code == NUMBER) ret += " " + number;
- else if (string != null) ret += " \"" + string + "\"";
- ret += "\n";
- if (left != null) ret += left.toString(indent + 2);
- if (right != null) ret += right.toString(indent + 2);
- if (next != null) ret += next.toString(indent);
- return ret;
- }
-
- public Expr(String s) { code = STRING; this.string = s; } // an identifier or label
- public Expr(Number n) { code = NUMBER; this.number = n; } // an identifier or label
- public Expr(int code) { this(code, null, null); }
- public Expr(int code, String s) { this.code = code; string = s; }
- public Expr(int code, Expr left) { this(code, left, null); }
- public Expr(int code, Expr left, Expr right) { this.code = code; this.left = left; this.right = right; }
+ /** gets a token and throws an exception if it is not <tt>code</tt> */
+ public void consume(int code) throws IOException {
+ if (getToken() != code)
+ throw new ParserException("expected " + codeToString[code] + ", got " + (op == -1 ? "EOL" : codeToString[op]));
}
-
- /** 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 {
- Expr ret = null;
- int tok = peekToken();
- boolean braced = tok == LC;
- if (requireBraces && !braced) throw new Error("expected {");
- if (braced) getToken();
- Expr head = null;
- Expr tail = null;
- OUTER: while(true) {
- Expr smt;
- switch(tok = peekToken()) {
- case -1: break OUTER;
- case LC: smt = parseBlock(true); break;
- case THROW: case RETURN: case ASSERT:
- getToken();
- smt = new Expr(tok, parseMaximalExpr());
- if (getToken() != SEMI) throw new Error("expected ;");
- break;
- case GOTO: case BREAK: case CONTINUE:
- getToken();
- if (getToken() == NAME)
- smt = new Expr(tok, new Expr(string));
- else if (tok == GOTO)
- throw new Error("goto must be followed by a label");
- else
- smt = new Expr(tok);
- if (getToken() != SEMI) throw new Error("expected ;");
- break;
- case RC:
- if (braced) getToken();
- break OUTER;
+ /** parses the largest possible expression */
+ public ForthBlock parseExpr() throws IOException { return parseExpr(null, -1); }
- case SEMI:
- getToken();
- if (!braced) break OUTER;
- continue;
-
- default:
- smt = parseMaximalExpr();
- if (smt == null) {
- if (head == null) throw new Error("empty statement list");
- break OUTER;
- }
- break;
- }
- if (head == null) head = tail = smt; else tail = (tail.next = smt);
- }
- return new Expr(LC, head);
+ /** return the largest expression beginning with prefix containing no operators of precedence below <tt>minPrecedence</tt> */
+ public ForthBlock parseExpr(ForthBlock prefix, int minPrecedence) throws IOException {
+ return parseExpr(prefix, minPrecedence, new ForthBlock(line, sourceName));
}
- /** throws an error if the next token is not <tt>code</tt> */
- public void expect(int code) throws IOException {
- int got = peekToken();
- if (got != code)
- throw new Error("expected " + codeToString[got] + ", got " + (got == -1 ? "EOL" : codeToString[got]));
- }
+ /** append the largest expression beginning with prefix containing no operators of precedence below <tt>minPrecedence</tt> */
+ public ForthBlock parseExpr(ForthBlock prefix, int minPrecedence, ForthBlock appendTo) throws IOException {
- /** parses the largest possible expression */
- public Expr parseMaximalExpr() throws IOException { return parseMaximalExpr(null, -1); }
- public Expr parseMaximalExpr(Expr prefix, int minPrecedence) throws IOException {
- Expr save = null;
- do {
- save = prefix;
- if (peekToken() == -1) break;
- prefix = parseSingleExpr(prefix, minPrecedence);
- if (prefix == null) throw new Error("parseSingleExpr_() returned null");
- } while (save != prefix);
- return prefix;
- }
-
- /** parses the smallest possible complete expression */
- public Expr parseSingleExpr() throws IOException { return parseSingleExpr(null, 0); }
+ int tok = getToken();
+ int curLine = line;
+ if (tok == -1) return prefix;
+ if (minPrecedence > 0 && precedence[tok] != 0)
+ if (precedence[tok] < minPrecedence || (precedence[tok] == minPrecedence && !isRightAssociative[tok]))
+ { pushBackToken(); return prefix; }
- /** parses the smallest possible complete expression beginning with prefix and only using operators with at least minPrecedence */
- public Expr parseSingleExpr(Expr prefix, int minPrecedence) throws IOException {
- Expr e1 = null, e2 = null, e3 = null, head = null, tail = null, ret = null;
+ if (prefix != null && mustStartExpression[tok]) { pushBackToken(); return prefix; }
+ if (prefix == null && cannotStartExpression[tok]) { pushBackToken(); return prefix; }
- int tok = peekToken();
- if (minPrecedence > 0 && tok < precedence.length && precedence[tok] != 0 && precedence[tok] <= minPrecedence) return prefix;
- getToken();
+ ForthBlock b = appendTo;
- // these case arms match the precedence of operators; each arm is a precedence level.
switch (tok) {
- case WITH: throw new Error("XWT does not allow the WITH keyword");
- case VOID: case RESERVED: throw new Error("reserved word that you shouldn't be using");
- case NAME: if (prefix != null) { pushBackToken(); return prefix; } else return parseMaximalExpr(new Expr(NAME, string), minPrecedence);
- case STRING: if (prefix != null) { pushBackToken(); return prefix; } else return new Expr(string);
- case NUMBER: if (prefix != null) { pushBackToken(); return prefix; } else return new Expr(number);
- case NULL: case TRUE: case FALSE: case NOP: if (prefix != null) { pushBackToken(); return prefix; } else return new Expr(tok);
-
- case COMMA: case ASSIGN: case GT: case GE: case OR: case AND:
- case BITOR: case BITXOR: case BITAND: case EQ: case NE: case LT:
- case LE: case SHEQ: case SHNE: case LSH: case RSH: case URSH:
- case ADD: case SUB: case MUL: case DIV: case MOD: case DOT:
- return new Expr(tok, prefix, parseMaximalExpr(null, precedence[tok]));
-
- case BITNOT: case INSTANCEOF:
- if (prefix != null) throw new Error("didn't expect non-null prefix!");
- return new Expr(tok, parseMaximalExpr(null, precedence[tok]));
+ case NUMBER: return parseExpr(b.add(ForthBlock.LITERAL, number), minPrecedence);
+ case STRING: return parseExpr(b.add(ForthBlock.LITERAL, string), minPrecedence);
+ case THIS: return parseExpr(b.add(THIS, null), minPrecedence);
+ case NULL: return parseExpr(b.add(ForthBlock.LITERAL, null), minPrecedence);
+ case TRUE: case FALSE: return parseExpr(b.add(ForthBlock.LITERAL, new Boolean(tok == TRUE)), minPrecedence);
+
+ 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.add(b.EXPR, prefix);
+ prefix.set(prefix.size() - 1, b.GET_PRESERVE, new Boolean(true));
+ prefix.add(prefix.EXPR, parseExpr(null, precedence[tok - 1]));
+ prefix.add(tok - 1);
+ prefix.add(b.PUT);
+ prefix.add(b.SWAP);
+ prefix.add(b.POP);
+ return parseExpr(b, minPrecedence);
+ }
case INC: case DEC:
if (prefix == null) {
// prefix
- return new Expr(tok, parseMaximalExpr(null, precedence[tok]));
+ ForthBlock subexp = parseExpr(null, precedence[tok]);
+ subexp.set(subexp.size() - 1, tok, new Boolean(true));
+ b.add(b.EXPR, subexp);
+ return parseExpr(b, minPrecedence);
} else {
// postfix
- return new Expr(tok, null, prefix);
+ prefix.set(prefix.size() - 1, tok, new Boolean(false));
+ b.add(b.EXPR, prefix);
+ return parseExpr(b, minPrecedence);
}
case LP:
if (prefix == null) { // grouping
- Expr r = parseMaximalExpr();
- expect(RP);
- return r;
+ b.add(EXPR, parseExpr());
+ consume(RP);
+ return parseExpr(b, minPrecedence);
} else { // invocation
+ int i = 0;
+ b.add(b.EXPR, prefix);
while(peekToken() != RP) {
- Expr e = parseMaximalExpr(null, precedence[COMMA]);
- if (head == null) head = tail = e; else tail = tail.next = e;
- tok = getToken();
- if (tok == RP) { pushBackToken(); break; }
- if (tok != COMMA) throw new Error("expected comma or right paren, got " + codeToString[tok]);
+ b.add(b.EXPR, parseExpr());
+ i++;
+ if (peekToken() == RP) break;
+ consume(COMMA);
}
- getToken();
- return new Expr(LP, prefix, head);
+ consume(RP);
+ b.add(b.CALL, new Integer(i));
+ return parseExpr(b, minPrecedence);
}
- case LB:
- if (prefix != null) {
- // subscripting
- e1 = parseSingleExpr();
- if (getToken() != RB) throw new Error("expected a right brace");
- return new Expr(LB, prefix, e1);
+ case BANG: case BITNOT: case INSTANCEOF: case TYPEOF: {
+ b.add(b.EXPR, parseExpr(null, precedence[tok]));
+ b.add(tok);
+ return parseExpr(b, minPrecedence);
+ }
+
+ case SUB:
+ if (prefix == null) {
+ consume(NUMBER);
+ return parseExpr(b.add(ForthBlock.LITERAL, new Double(number.doubleValue() * -1)), minPrecedence);
+ }
+ // fall through
+ 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: {
+ b.add(b.EXPR, prefix);
+ b.add(b.EXPR, parseExpr(null, precedence[tok]));
+ b.add(tok);
+ return parseExpr(b, minPrecedence);
+ }
+
+ case OR: case AND: {
+ b.add(b.LITERAL, tok == AND ? new Boolean(false) : new Boolean(true));
+ b.add(b.EXPR, prefix);
+ b.add(tok == AND ? b.JF : b.JT, new Integer(3));
+ b.add(b.POP);
+ b.add(b.EXPR, parseExpr(null, precedence[tok]));
+ return parseExpr(b, minPrecedence);
+ }
+
+ case NAME: {
+ String name = string;
+ if (peekToken() == ASSIGN) {
+ consume(ASSIGN);
+ b.add(THIS);
+ b.add(ForthBlock.LITERAL, name);
+ b.add(ForthBlock.EXPR, parseExpr(null, minPrecedence));
+ b.add(ForthBlock.PUT);
+ b.add(ForthBlock.SWAP);
+ b.add(ForthBlock.POP);
} else {
- // array ctor
- tok = getToken();
+ b.add(THIS);
+ b.add(ForthBlock.LITERAL, name);
+ b.add(ForthBlock.GET);
+ }
+ return parseExpr(b, minPrecedence);
+ }
+
+ case DOT: {
+ consume(NAME);
+ String target = string;
+ b.add(b.EXPR, prefix);
+ if (peekToken() == ASSIGN) {
+ consume(ASSIGN);
+ ForthBlock val = parseExpr();
+ b.add(b.LITERAL, target);
+ b.add(b.EXPR, val);
+ b.add(b.PUT);
+ b.add(b.SWAP);
+ b.add(b.POP);
+ } else {
+ b.add(b.LITERAL, target);
+ b.add(b.GET);
+ }
+ return parseExpr(b, minPrecedence);
+ }
+
+ case LB: {
+ if (prefix == null) {
+ b.add(b.ARRAY, new Integer(0));
+ int i = 0;
while(true) {
- if (tok == RB) return new Expr(LB, prefix, head);
- if (head == null) head = tail = parseSingleExpr(); else tail = tail.next = parseSingleExpr();
- tok = getToken();
- if (tok != COMMA && tok != RP) throw new Error("expected right bracket or comma");
+ ForthBlock e = parseExpr();
+ if (e == null && peekToken() == RB) { consume(RB); return parseExpr(b, minPrecedence); }
+ b.add(b.LITERAL, new Integer(i++));
+ if (e == null) b.add(b.LITERAL, null);
+ else b.add(b.EXPR, e);
+ b.add(b.PUT);
+ b.add(b.POP);
+ if (peekToken() == RB) { consume(RB); return parseExpr(b, minPrecedence); }
+ consume(COMMA);
}
+ } else {
+ b.add(b.EXPR, prefix);
+ b.add(b.EXPR, parseExpr());
+ consume(RB);
+ if (peekToken() == ASSIGN) {
+ consume(ASSIGN);
+ b.add(b.EXPR, parseExpr());
+ b.add(b.PUT);
+ b.add(b.SWAP);
+ b.add(b.POP);
+ } else {
+ b.add(b.GET);
+ }
+ return parseExpr(b, minPrecedence);
}
-
- case LC:
- if (prefix != null) throw new Error("didn't expect non-null prefix");
- tok = getToken();
- while(true) {
- if (tok == RC) return new Expr(LC, head);
- if (tok != NAME) throw new Error("expecting name");
- Expr name = parseSingleExpr();
- if (tok != COLON) throw new Error("expecting colon");
- e1 = new Expr(COLON, name, parseSingleExpr());
- 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 HOOK:
- e2 = parseSingleExpr();
- if (getToken() != COLON) throw new Error("expected colon to close ?: expression");
- e3 = parseSingleExpr();
- e2.next = e3;
- return new Expr(HOOK, prefix, e2);
-
- case SWITCH: {
- if (prefix != null) throw new Error("didn't expect non-null prefix");
- if (getToken() != LP) throw new Error("expected left paren");
- Expr switchExpr = parseSingleExpr();
- if (getToken() != RP) throw new Error("expected left paren");
- if (getToken() != LC) throw new Error("expected left brace");
- Expr firstExpr = null;
- Expr lastExpr = null;
+ }
+
+ case LC: {
+ b.add(b.OBJECT, null);
+ if (peekToken() == RC) { consume(RC); return parseExpr(b, minPrecedence); }
while(true) {
- if (getToken() != CASE) throw new Error("expected CASE");
- Expr caseExpr = parseSingleExpr();
- 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 (peekToken() != NAME && peekToken() != STRING) throw new Error("expected NAME or STRING");
+ getToken();
+ b.add(b.LITERAL, string);
+ consume(COLON);
+ b.add(b.EXPR, parseExpr());
+ b.add(b.PUT);
+ b.add(b.POP);
+ if (peekToken() == RC) { consume(RC); return parseExpr(b, minPrecedence); }
+ consume(COMMA);
+ if (peekToken() == RC) { consume(RC); return parseExpr(b, minPrecedence); }
}
}
- case FUNCTION: {
- if (prefix != null) throw new Error("didn't expect non-null prefix");
- 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(NAME, 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();
- }
- return new Expr(FUNCTION, formalArgs, parseBlock(true));
+ case HOOK: {
+ b.add(b.EXPR, prefix);
+ b.add(b.JF, new Integer(3));
+ b.add(b.EXPR, parseExpr());
+ b.add(b.JMP, new Integer(2));
+ consume(COLON);
+ b.add(b.EXPR, parseExpr());
+ return parseExpr(b, minPrecedence);
}
- case VAR:
- if (prefix != null) throw new Error("didn't expect non-null prefix");
- while(true) {
- if (getToken() != NAME) throw new Error("variable declarations must start with a variable name");
- Expr name = new Expr(NAME, string);
- Expr initVal = null;
- tok = peekToken();
- Expr e = null;
- if (tok == ASSIGN) {
- getToken();
- initVal = parseSingleExpr();
- tok = peekToken();
- e = new Expr(ASSIGN, name, initVal);
+ case Tokens.FUNCTION: {
+ consume(LP);
+ int numArgs = 0;
+ ForthBlock b2 = new ForthBlock(curLine, sourceName);
+ b2.add(THIS);
+ b2.add(b.SWAP);
+ b2.add(b.LITERAL, "arguments");
+ b2.add(b.LITERAL, "arguments");
+ b2.add(b.DECLARE);
+ b2.add(b.SWAP);
+ b2.add(b.PUT);
+ b2.add(b.SWAP);
+ b2.add(b.POP);
+ if (peekToken() == RP) consume(RP);
+ else while(true) {
+ if (peekToken() == COMMA) {
+ // FIXME: pop an item off the stack here?
+ consume(COMMA);
} else {
- e = new Expr(NAME, name);
+ consume(NAME);
+
+ // declare the name
+ b2.add(b.LITERAL, string);
+ b2.add(b.DECLARE);
+
+ // retrieve it from the arguments array
+ b2.add(b.LITERAL, new Integer(numArgs));
+ b2.add(b.GET_PRESERVE);
+ b2.add(b.SWAP);
+ b2.add(b.POP);
+
+ // put it to the current scope
+ b2.add(THIS);
+ b2.add(b.SWAP);
+ b2.add(b.LITERAL, string);
+ b2.add(b.SWAP);
+ b2.add(b.PUT);
+
+ // clean the stack
+ b2.add(b.POP);
+ b2.add(b.POP);
+
+ if (peekToken() == RP) { consume(RP); break; }
+ consume(COMMA);
}
- if (head == null) head = tail = e; else tail = tail.next = e;
- if (tok != COMMA) break;
- getToken();
+ numArgs++;
}
- return new Expr(VAR, head);
+ // pop off the arguments array
+ b2.add(b.POP);
+ parseStatement(true, b2);
+ b2.add(b.LITERAL, null);
+ b2.add(RETURN);
+ return parseExpr(b.add(OpCodes.FUNCTION, b2), minPrecedence);
+ }
+
+ default: pushBackToken(); return prefix;
+ }
+ }
+
+ /** a block is either a single statement or a list of statements surrounded by curly braces; all expressions are also statements */
+ public ForthBlock parseStatement() throws IOException {
+ ForthBlock ret = new ForthBlock(line, sourceName);
+ ret.add(ret.LITERAL, null);
+ parseStatement(false, ret);
+ if (ret.size() == 1) return null;
+ return ret;
+ }
+
+ public void parseStatement(boolean requireBraces) throws IOException {
+ parseStatement(requireBraces, new ForthBlock(line, sourceName));
+ }
+ public void parseStatement(boolean requireBraces, ForthBlock b) throws IOException {
+ int tok = peekToken();
+ if (tok == -1) return;
+ boolean braced = tok == LC;
+ if (requireBraces && !braced) throw new ParserException("expected {, got " + codeToString[tok]);
+ if (braced) consume(LC);
+ int curLine = line;
+ while(true) {
+ switch(tok = peekToken()) {
- case TRY: {
- // We deliberately allow you to omit braces in catch{}/finally{} if they are single statements...
- if (prefix != null) throw new Error("didn't expect non-null prefix");
- Expr tryBlock = parseBlock(true);
- while ((tok = peekToken()) == CATCH || tok == FINALLY) {
+ case THROW: case RETURN: case ASSERT: {
getToken();
- if (getToken() != LP) throw new Error("expected (");
- if (getToken() != NAME) throw new Error("expected name");
- Expr name = new Expr(NAME, string);
- if (getToken() != RP) throw new Error("expected )");
- e1 = new Expr(tok, name, parseBlock(false));
- if (head == null) head = tail = e1; else tail = tail.next = e1;
+ if (tok == RETURN && peekToken() == SEMI) b.add(b.LITERAL, null);
+ else b.add(b.EXPR, parseExpr());
+ consume(SEMI);
+ b.add(tok);
+ break;
}
- if (head == null) throw new Error("try without catch or finally");
- return new Expr(TRY, tryBlock, head);
- }
- case IF: case WHILE: {
- if (prefix != null) throw new Error("didn't expect non-null prefix");
- if (getToken() != LP) throw new Error("expected left paren");
- Expr parenExpr = parseMaximalExpr(null, -1);
- int t;
- if ((t = getToken()) != RP) throw new Error("expected right paren, but got " + codeToString[t]);
- Expr firstBlock = parseBlock(false);
- if (tok == IF && peekToken() == ELSE) {
+ case BREAK: case CONTINUE: {
getToken();
- firstBlock.next = parseBlock(false);
- return new Expr(tok, parenExpr, firstBlock);
+ if (peekToken() == NAME) consume(NAME);
+ b.add(tok, string);
+ consume(SEMI);
+ break;
+ }
+
+ case SEMI:
+ consume(SEMI);
+ if (!braced) return;
+ break;
+
+ case VAR: {
+ consume(VAR);
+ b.add(THIS); // push the current scope
+ while(true) {
+ consume(NAME);
+ String name = string;
+ b.add(b.LITERAL, name); // push the name to be declared
+ b.add(b.DECLARE); // declare it
+ if (peekToken() == ASSIGN) { // if there is an '=' after the variable name
+ b.add(b.LITERAL, name); // put the var name back on the stack
+ consume(ASSIGN);
+ b.add(b.EXPR, parseExpr());
+ b.add(b.PUT);
+ b.add(b.POP);
+ }
+ if (peekToken() != COMMA) break;
+ consume(COMMA);
+ }
+ b.add(b.POP);
+ if (peekToken() == SEMI) consume(SEMI);
+ break;
+ }
+
+ case IF: {
+ consume(IF);
+ consume(LP);
+ b.add(b.EXPR, parseExpr());
+ consume(RP);
+ b.add(b.JF, new Integer(4));
+ b.add(b.EXPR, parseStatement());
+ b.add(b.POP);
+ b.add(b.JMP, new Integer(3));
+ if (peekToken() == ELSE) {
+ consume(ELSE);
+ b.add(b.EXPR, parseStatement());
+ b.add(b.POP);
+ } else {
+ b.add(b.JMP, new Integer(1)); // nop
+ b.add(b.JMP, new Integer(1)); // nop
+ }
+ break;
}
- return new Expr(tok, parenExpr, firstBlock);
- }
- case IN: return prefix;
- case FOR:
- if (prefix != null) throw new Error("didn't expect non-null prefix");
- if (getToken() != LP) throw new Error("expected left paren");
- e1 = parseMaximalExpr(null, -1);
- if (e1.code == NAME && peekToken() == IN) {
- getToken();
- e2 = parseMaximalExpr(null, -1);
- if (getToken() != RP) throw new Error("expected right paren");
- return new Expr(FOR, new Expr(IN, e1, e2), parseBlock(false));
+ case WHILE: {
+ consume(WHILE);
+ consume(LP);
+ ForthBlock loop = new ForthBlock(curLine, sourceName);
+ b.add(loop.LOOP, loop);
+
+ loop.add(loop.POP);
+ loop.add(loop.EXPR, parseExpr());
+ loop.add(loop.JT, new Integer(2));
+ loop.add(Lexer.BREAK);
+ consume(RP);
+ parseStatement(false, loop);
+
+ // if we fall out of the end, definately continue
+ loop.add(CONTINUE);
+ break;
+ }
+
+ case SWITCH: {
+ consume(SWITCH);
+ consume(LP);
+ ForthBlock loop = new ForthBlock(curLine, sourceName);
+ b.add(loop.LOOP, loop);
+ loop.add(loop.EXPR, parseExpr());
+ consume(RP);
+ consume(LC);
+ while(true) {
+ ForthBlock caseForthBlock;
+ tok = getToken();
+ if (tok == CASE) {
+ loop.add(loop.DUP);
+ loop.add(loop.EXPR, parseExpr());
+ loop.add(EQ);
+ loop.add(loop.JF, new Integer(2));
+ } else if (tok != DEFAULT) throw new ParserException("expected CASE or DEFAULT");
+ consume(COLON);
+ ForthBlock b2 = new ForthBlock(curLine, sourceName);
+ ForthBlock e1 = null;
+ while(peekToken() != CASE && peekToken() != DEFAULT && peekToken() != RC) {
+ if ((e1 = parseStatement()) == null) break;
+ b2.add(b.EXPR, e1);
+ b2.add(b.POP);
+ }
+ loop.add(loop.EXPR, b2);
+ if (peekToken() == RC) {
+ consume(RC);
+ loop.add(BREAK);
+ break;
+ }
+ }
+ break;
+ }
+
+ case DO: {
+ consume(DO);
+ ForthBlock loop = new ForthBlock(curLine, sourceName);
+ b.add(loop.LOOP, loop);
+
+ parseStatement(false, loop);
+ consume(WHILE);
+ consume(LP);
+ loop.add(loop.EXPR, parseExpr());
+ loop.add(loop.JT, new Integer(2));
+ loop.add(Lexer.BREAK);
+ loop.add(Lexer.CONTINUE);
+ consume(RP);
+ consume(SEMI);
+ break;
+ }
+
+ case TRY: {
+ // FIXME: don't just ignore this!
+ // We deliberately allow you to omit braces in catch{}/finally{} if they are single statements...
+ consume(TRY);
+ parseStatement(true, b);
+
+ if (peekToken() == CATCH) {
+ getToken();
+ consume(LP);
+ consume(NAME);
+ consume(RP);
+ parseStatement(); // just discard the catchblock
+ }
+
+ if (peekToken() == FINALLY) {
+ consume(FINALLY);
+ parseStatement(false, b);
+ }
+ break;
+ }
+
+ case FOR: {
+ consume(FOR);
+ consume(LP);
+
+ tok = getToken();
+ if (tok == VAR) tok = getToken();
+ String varName = string;
+ boolean forIn = peekToken() == IN;
+ pushBackToken(tok, varName);
+
+ if (forIn) {
+ consume(NAME);
+ consume(IN);
+ b.add(b.EXPR, parseExpr());
+ b.add(b.PUSHKEYS);
+ b.add(b.LITERAL, "length");
+ b.add(b.GET);
+ consume(RP);
+ ForthBlock b2 = new ForthBlock(curLine, sourceName);
+ b.add(b.SCOPE, b2);
+ b2.add(b.LITERAL, new Integer(1));
+ b2.add(SUB);
+ b2.add(b.DUP);
+ b2.add(b.LITERAL, new Integer(0));
+ b2.add(LT);
+ b2.add(b.JT, new Integer(7));
+ b2.add(b.GET_PRESERVE);
+ b2.add(b.LITERAL, varName);
+ b2.add(b.LITERAL, varName);
+ b2.add(b.DECLARE);
+ b2.add(b.PUT);
+ b2.add(b.EXPR, parseStatement());
+ //b2.add(b.LITERAL, null);
+ break;
} else {
- if (getToken() != SEMI) throw new Error("expected ;");
- e2 = parseMaximalExpr(null, -1);
- if (getToken() != SEMI) throw new Error("expected ;");
- e3 = parseMaximalExpr(null, -1);
- if (getToken() != RP) throw new Error("expected right paren");
- return new Expr(LC, e1, new Expr(WHILE, e2, new Expr(LC, parseBlock(false), e3)));
+ ForthBlock b2 = new ForthBlock(curLine, sourceName);
+ b.add(b.SCOPE, b2);
+ b.add(b.POP);
+
+ ForthBlock e1 = parseExpr();
+ if (e1 == null) e1 = new ForthBlock(curLine, sourceName, b.LITERAL, null);
+
+ b2.add(b.EXPR, e1);
+ b2.add(b.POP);
+ consume(SEMI);
+ ForthBlock e2 = parseExpr();
+ consume(SEMI);
+ ForthBlock e3 = parseExpr();
+ consume(RP);
+
+ if (e2 == null) e2 = new ForthBlock(curLine, sourceName, b.LITERAL, null);
+ if (e3 == null) e3 = new ForthBlock(curLine, sourceName, b.LITERAL, null);
+
+ ForthBlock b3 = new ForthBlock(curLine, sourceName);
+ b2.add(b.LOOP, b3);
+ b2.add(b.LITERAL, null);
+ b3.add(b.JT, new Integer(3));
+ b3.add(b.EXPR, e3);
+ b3.add(b.POP);
+ b3.add(b.EXPR, e2);
+ b3.add(b.JT, new Integer(2));
+ b3.add(BREAK);
+ parseStatement(false, b3);
+ b3.add(BREAK);
+ break;
}
-
- case DO: {
- if (prefix != null) throw new Error("didn't expect non-null prefix");
- Expr firstBlock = parseBlock(false);
- if (getToken() != WHILE) throw new Error("expecting WHILE");
- if (getToken() != LP) throw new Error("expected left paren");
- Expr whileExpr = parseSingleExpr();
- if (getToken() != RP) throw new Error("expected right paren");
- if (getToken() != SEMI) throw new Error("semicolon");
- return new Expr(DO, firstBlock, whileExpr);
}
- default:
- pushBackToken();
- return prefix;
+ case NAME: {
+ consume(NAME);
+ String name = string;
+ if (peekToken() == COLON) {
+ consume(COLON);
+ b.add(ForthBlock.LABEL, string);
+ break;
+ } else {
+ pushBackToken(NAME, name);
+ // fall through to default case
+ }
+ }
+ // fall through
+ case RC:
+ if (tok == RC && braced) { consume(RC); return; }
+ // fall through
+ default: {
+ ForthBlock ret = parseExpr();
+ if (ret == null) return;
+ b.add(b.EXPR, ret);
+ b.add(b.POP);
+ if (peekToken() == SEMI) consume(SEMI);
+ break;
+ }
+ }
+
+ if (!braced) return;
}
}
+ class ParserException extends RuntimeException {
+ public ParserException(String s) { super(sourceName + ":" + line + " " + s); }
+ }
+
}
projects / org.ibex.core.git / blobdiff