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#include "as_parser.h"
#include <stdlib.h>
// BNF
// ===
//
// <prog> ::= <stmts>
// <stmts> ::= <stmt> <newline> | <stmt> <stmts>
// <stmt> ::= <label> <instr> | <instr> | <label>
// <instr> ::= <op> | <op> <arg> | <op> <tag>
// <label> ::= <tag> :
// <op> ::= add | sub | mul | div | mod | eq
Prog* parseProg(TokenStream *ts) {
Prog *p = malloc(sizeof(Prog));
p->stmts = parseStmts(ts);
return p;
}
Stmts* parseStmts(TokenStream *ts) {
Stmts *ss = malloc(sizeof(Stmts));
ss->stmts = malloc(sizeof(Stmt*));
ss->stmts[0] = NULL;
int capacity = 0;
int len = 0;
while (peekToken(ts)->type != ENDOFFILE) {
Stmt *s = parseStmt(ts);
if (len == capacity) {
capacity = capacity * 2 + 1;
ss->stmts = realloc(ss->stmts, sizeof(Stmt*) * capacity);
}
ss->stmts[len] = s;
len++;
}
ss->stmts[len] = NULL;
return ss;
}
Label* parseLabel(TokenStream *ts) {
Token *t = nextToken(ts);
if (t->type != TAG) {
fprintf(stderr, "%d:%d Expect LABEL.\n", t->line, t->col);
exit(-1);
}
Label *l = malloc(sizeof(Label));
l->name = t->sval;
t = nextToken(ts);
if (t->type != COLON) {
fprintf(stderr, "%d:%d Expect COLON.\n", t->line, t->col);
exit(-1);
}
return l;
}
Stmt* parseStmt(TokenStream *ts) {
Token *t = peekToken(ts);
if (t->type == TAG) {
Label *l = parseLabel(ts);
t = peekToken(ts);
if (t->type == COLON) {
nextToken(ts);
return (Stmt*)l;
} else {
Instr *i = parseInstr(ts);
Stmt *s = malloc(sizeof(Stmt));
s->label = l;
s->instr = i;
return s;
}
} else {
Instr *i = parseInstr(ts);
Stmt *s = malloc(sizeof(Stmt));
s->label = NULL;
s->instr = i;
return s;
}
}
// parse op
Op parseOp(TokenStream *ts) {
Token *t = nextToken(ts);
Op op;
if (t->type == OP) {
op = str2op(t->sval);
if (op == OPEND) {
fprintf(stderr, "%d:%d Invalid OP.\n", t->line, t->col);
exit(-1);
}
} else {
fprintf(stderr, "%d:%d Expect OP.\n", t->line, t->col);
exit(-1);
}
return op;
}
Instr* parseInstr(TokenStream *ts) {
Token *t = nextToken(ts);
Instr *i = malloc(sizeof(Instr));
i->tagName = NULL;
if (t->type == OP) {
i->op = parseOp(ts);
t = peekToken(ts);
if (t->type == ARG) {
Arg *a = malloc(sizeof(Arg));
a->ival = t->ival;
a->fval = t->fval;
i->arg = a;
nextToken(ts);
} else if (t->type == TAG) {
i->tagName = t->sval;
nextToken(ts);
}
}
return i;
}
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