// FIXME: for..in
public class Parser extends Lexer {
- public static void main(String[] s) throws Exception { System.out.println(new Parser(new InputStreamReader(System.in)).parseExpr()); }
+ public static void main(String[] s) throws Exception {
+ Parser p = new Parser(new InputStreamReader(System.in));
+ while(true) {
+ Expr block = p.parseBlock(false);
+ if (block == null) return;
+ System.out.println(block);
+ if (p.peekToken() == -1) return;
+ }
+ }
public Parser(Reader r) throws IOException { super(r); }
private Parser skipToken() throws IOException { getToken(); return this; }
String ret = "";
for(int i=0; i<indent; i++) ret += " ";
ret += codeToString[code];
- if (code == STRING) ret += " \"" + string + "\"";
- else if (code == NUMBER) ret += " " + number;
+ 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 += left.toString(indent + 2);
- if (extra != null) ret += left.toString(indent + 2);
+ if (right != null) ret += right.toString(indent + 2);
+ if (extra != null) ret += extra.toString(indent + 2);
+ if (next != null) ret += next.toString(indent);
// FIXME: next
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, null); }
+ public Expr(int code, String s) { this.code = code; string = s; }
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; }
}
- /** 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;
- }
-
/** 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();
- if (requireBraces && tok != LC) throw new Error("expected {");
- if (tok != LC) return parseStatement();
- skipToken();
+ boolean braced = tok == LC;
+ if (requireBraces && !braced) throw new Error("expected {");
+ if (braced) skipToken();
Expr head = null;
Expr tail = null;
- while(peekToken() != RC)
- if (head == null) head = tail = parseStatement(); else tail = tail.next = parseStatement();
- skipToken();
+ OUTER: while(true) {
+ Expr smt;
+ switch(tok = peekToken()) {
+ case -1: break OUTER;
+ case LC: smt = parseBlock(true); break;
+ case THROW: case RETURN: case ASSERT:
+ smt = new Expr(tok, skipToken().parseExpr());
+ if (getToken() != SEMI) throw new Error("expected ;");
+ break;
+ case GOTO: case BREAK: case CONTINUE:
+ skipToken();
+ 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) skipToken();
+ break OUTER;
+
+ case SEMI:
+ skipToken();
+ if (!braced) break OUTER;
+ continue;
+
+ default:
+ smt = parseExpr();
+ 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);
}
precedence[MUL] = precedence[DIV] = precedence[MOD] = 13;
precedence[BITNOT] = precedence[INSTANCEOF] = 14;
precedence[INC] = precedence[DEC] = 15;
+ precedence[LP] = 16;
+ precedence[DOT] = 17;
}
// called after each parseExpr(); returns null if we can't make the expression any bigger
- public Expr parseExpr() throws IOException { return parseExpr(null, 0); }
+ public Expr parseExpr() throws IOException { return parseExpr_(null, 0); }
public Expr parseExpr(Expr prefix, int minPrecedence) throws IOException {
+ Expr save = null;
+ do {
+ save = prefix;
+ if (peekToken() == -1) break;
+ prefix = parseExpr_(prefix, minPrecedence);
+ if (prefix == null) throw new Error("parseExpr_() returned null");
+ } while (save != prefix);
+ return prefix;
+ }
+
+ public Expr parseExpr_(Expr prefix, int minPrecedence) throws IOException {
Expr e1 = null;
Expr e2 = null;
Expr e3 = null;
Expr ret = null;
int tok = getToken();
- if (minPrecedence != 0 && tok < precedence.length && precedence[tok] != 0 && precedence[tok] < minPrecedence)
- return null;
+ if (minPrecedence != -1 && minPrecedence != 0 && tok < precedence.length && precedence[tok] != 0 && precedence[tok] <= minPrecedence) {
+ pushBackToken();
+ return prefix;
+ }
// these case arms match the precedence of operators; each arm is a precedence level.
switch (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 ADD: case SUB: case MUL: case DIV: case MOD: case DOT:
return new Expr(tok, prefix, parseExpr(null, precedence[tok]));
-
+
case BITNOT: case INSTANCEOF:
return new Expr(tok, parseExpr(null, precedence[tok]));
-
+
// FIXME: this isn't 100% right
case INC: case DEC:
return new Expr(tok, prefix, (tok == INC || tok == DEC) ? null : parseExpr());
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");
+ if (prefix == null) {
+ // grouping
+ Expr r = parseExpr(null, -1);
+ if ((tok = getToken()) != RP) throw new Error("expected ), got " + codeToString[tok]);
+ return r;
+
+ } else {
+ // invocation
+ while(peekToken() != RP) {
+ Expr e = parseExpr(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]);
+ }
+ skipToken();
+ return new Expr(LP, prefix, head);
}
- return new Expr(LP, prefix, head);
case LB:
if (prefix != null) {
if (prefix != null) throw new Error("didn't expect non-null prefix");
tok = getToken();
while(true) {
- if (tok == RP) return new Expr(LC, head);
+ if (tok == RC) return new Expr(LC, head);
if (tok != NAME) throw new Error("expecting name");
Expr name = parseExpr();
if (tok != COLON) throw new Error("expecting colon");
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; }
+ 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(tok, formalArgs, parseBlock(true));
+ return new Expr(FUNCTION, formalArgs, parseBlock(true));
}
case STRING:
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, new Expr(string));
+ Expr name = new Expr(NAME, string);
Expr initVal = null;
tok = peekToken();
+ Expr e = null;
if (tok == ASSIGN) {
skipToken();
initVal = parseExpr();
tok = peekToken();
+ e = new Expr(ASSIGN, name, initVal);
+ } else {
+ e = new Expr(NAME, name);
}
- Expr e = new Expr(VAR, name, initVal);
if (head == null) head = tail = e; else tail = tail.next = e;
if (tok != COMMA) break;
skipToken();
}
return new Expr(VAR, head);
-
+
+ case NULL:
+ return new Expr(NULL);
+
case NAME:
- if (prefix != null) throw new Error("didn't expect non-null prefix");
- return new Expr(string);
-
+ if (prefix != null) { pushBackToken(); return prefix; }
+ return parseExpr(new Expr(NAME, string), minPrecedence);
+
case TRUE: case FALSE: case NOP:
if (prefix != null) throw new Error("didn't expect non-null prefix");
return new Expr(tok);
// FIXME: 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)
- if (head == null) head = tail = parseBlock(false); else tail = tail.next = parseBlock(false);
+ while ((tok = peekToken()) == CATCH) {
+ skipToken();
+ if (getToken() != LP) throw new Error("expected (");
+ if (getToken() != NAME) throw new Error("expected name");
+ // FIXME: record the name
+ if (getToken() != RP) throw new Error("expected )");
+ 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);
}
+
+ // FIXME: a.b=c becomes PUT(a,b,c) not ASSIGN(DOT(a,b),c)
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 = parseExpr();
- if (getToken() != RP) throw new Error("expected right paren");
+ Expr parenExpr = parseExpr(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) return new Expr(tok, parenExpr, firstBlock, skipToken().parseBlock(false));
+ if (tok == IF && peekToken() == ELSE)
+ return new Expr(tok, parenExpr, firstBlock, skipToken().parseBlock(false));
return new Expr(tok, parenExpr, firstBlock);
}
// FIXME: for..in
if (prefix != null) throw new Error("didn't expect non-null prefix");
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 )
+ e1 = parseExpr(null, -1);
+ if (getToken() != SEMI) throw new Error("expected ;");
+ e2 = parseExpr(null, -1);
+ if (getToken() != SEMI) throw new Error("expected ;");
+ e3 = parseExpr(null, -1); // 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));
default:
pushBackToken();
- return null;
+ return prefix;
}
}
projects / org.ibex.core.git / commitdiff