import java.io.*;
// FIXME: for..in
-// FIXME: delete keyword
public class Parser extends Lexer {
+ public static void main(String[] s) throws Exception { System.out.println(new Parser(new InputStreamReader(System.in)).parseExpr()); }
+
public Parser(Reader r) throws IOException { super(r); }
private Parser skipToken() throws IOException { getToken(); return this; }
Expr next = null; // if this expr is part of a list
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 == STRING) ret += " \"" + string + "\"";
+ else if (code == NUMBER) ret += " " + number;
+ 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);
+ // FIXME: next
+ return ret;
+ }
- public Expr(String s) { this.string = s; } // an identifier or label
+ 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, Expr left) { this(code, left, null, null); }
public Expr(int code, Expr left, Expr right) { this(code, left, right, null); }
return new Expr(LC, head);
}
- /** 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.
- */
- public Expr parseExpr() throws IOException {
- Expr e = parseStarter();
- while(true) {
- Expr e2 = parseContinuer(e);
- if (e2 == null) return e;
- e = e2;
- }
+ static byte[] precedence = new byte[MAX_TOKEN + 1];
+ static {
+ precedence[COMMA] = 1;
+ precedence[ASSIGN] = 2;
+ precedence[GT] = precedence[GE] = 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;
}
- public Expr parseStarter() throws IOException {
+ // 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(Expr prefix, int minPrecedence) throws IOException {
Expr e1 = null;
Expr e2 = null;
Expr e3 = null;
Expr head = null;
Expr tail = null;
+ Expr ret = null;
int tok = getToken();
- switch(tok) {
+
+ if (minPrecedence != 0 && tok < precedence.length && precedence[tok] != 0 && precedence[tok] < minPrecedence)
+ return null;
+
+ // 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:
+ 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");
+ }
+ return new Expr(LP, prefix, head);
+
+ case LB:
+ if (prefix != null) {
+ // subscripting
+ e1 = parseExpr();
+ if (getToken() != RB) throw new Error("expected a right brace");
+ return new Expr(LB, prefix, e1);
+ } else {
+ // array ctor
+ tok = getToken();
+ while(true) {
+ if (tok == RB) return new Expr(LB, prefix, 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");
+ }
+ }
+
+ case LC:
+ 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 != 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 HOOK:
+ e2 = parseExpr();
+ if (getToken() != COLON) throw new Error("expected colon to close ?: expression");
+ e3 = parseExpr();
+ return new Expr(HOOK, prefix, e2, e3);
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 = parseExpr();
if (getToken() != RP) throw new Error("expected left paren");
}
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();
return new Expr(tok, formalArgs, parseBlock(true));
}
+ case STRING:
+ return new Expr(string);
+
+ case NUMBER:
+ return new Expr(number);
+
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(string);
+ Expr name = new Expr(NAME, new Expr(string));
Expr initVal = null;
tok = peekToken();
if (tok == ASSIGN) {
}
return new Expr(VAR, head);
- 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 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");
- }
-
case NAME:
+ if (prefix != null) throw new Error("didn't expect non-null prefix");
return new Expr(string);
- case INC: case DEC: case TYPEOF:
- return new Expr(tok, parseExpr());
-
case TRUE: case FALSE: case NOP:
+ if (prefix != null) throw new Error("didn't expect non-null prefix");
return new Expr(tok);
case TRY: {
// 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);
}
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");
case FOR:
// 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();
//return new Expr(FOR, e1, e2, e3, parseBlock(false));
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");
case WITH:
throw new Error("WITH not yet implemented"); // FIXME
- default: throw new Error("I wasn't expecting a " + tok);
- }
- }
-
- // 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");
- }
- 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:
pushBackToken();
return null;
projects / org.ibex.core.git / blobdiff