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85e5642b2a
unleashed-firmware/lib/mjs/mjs_parser.c
Anna Antonenko 85e5642b2a
[FL-3918] Full-fledged JS SDK + npm packages (#3963) 
* feat: js sdk
* refactor: move js back where it belongs
* docs: generate docs using typedoc
* feat: sdk versioning scheme
* ci: silence pvs warning
* docs: bring back old incomplete js docs
* style: readAnalog naming
* fix: rename script compatibility screens

Co-authored-by: あく <alleteam@gmail.com>
2024-10-31 11:42:57 +09:00

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/*
* Copyright (c) 2017 Cesanta Software Limited
* All rights reserved
*/
#include "common/cs_varint.h"
#include "mjs_bcode.h"
#include "mjs_core.h"
#include "mjs_internal.h"
#include "mjs_parser.h"
#include "mjs_string.h"
#include "mjs_tok.h"
#ifndef MAX_TOKS_IN_EXPR
#define MAX_TOKS_IN_EXPR 40
#endif
#define FAIL_ERR(p, code) \
do { \
mjs_set_errorf( \
p->mjs, code, "parse error at line %d: [%.*s]", p->line_no, 10, p->tok.ptr); \
return code; \
} while(0)
#define pnext1(p) \
do { \
LOG(LL_VERBOSE_DEBUG, (" PNEXT %d", __LINE__)); \
pnext(p); \
} while(0)
#define SYNTAX_ERROR(p) FAIL_ERR(p, MJS_SYNTAX_ERROR)
#undef EXPECT
#define EXPECT(p, t) \
if((p)->tok.tok != (t)) \
SYNTAX_ERROR(p); \
else \
pnext1(p);
static mjs_err_t parse_statement(struct pstate* p);
static mjs_err_t parse_expr(struct pstate* p);
static int ptest(struct pstate* p) {
struct pstate saved = *p;
int tok = pnext(p);
*p = saved;
return tok;
}
static int s_unary_ops[] = {
TOK_NOT,
TOK_TILDA,
TOK_PLUS_PLUS,
TOK_MINUS_MINUS,
TOK_KEYWORD_TYPEOF,
TOK_MINUS,
TOK_PLUS,
TOK_EOF};
static int s_comparison_ops[] = {TOK_LT, TOK_LE, TOK_GT, TOK_GE, TOK_EOF};
static int s_postfix_ops[] = {TOK_PLUS_PLUS, TOK_MINUS_MINUS, TOK_EOF};
static int s_equality_ops[] = {TOK_EQ, TOK_NE, TOK_EQ_EQ, TOK_NE_NE, TOK_EOF};
static int s_assign_ops[] = {
TOK_ASSIGN,
TOK_PLUS_ASSIGN,
TOK_MINUS_ASSIGN,
TOK_MUL_ASSIGN,
TOK_DIV_ASSIGN,
TOK_REM_ASSIGN,
TOK_LSHIFT_ASSIGN,
TOK_RSHIFT_ASSIGN,
TOK_URSHIFT_ASSIGN,
TOK_AND_ASSIGN,
TOK_XOR_ASSIGN,
TOK_OR_ASSIGN,
TOK_EOF};
static int findtok(int* toks, int tok) {
int i = 0;
while(tok != toks[i] && toks[i] != TOK_EOF)
i++;
return toks[i];
}
static void emit_op(struct pstate* pstate, int tok) {
assert(tok >= 0 && tok <= 255);
emit_byte(pstate, OP_EXPR);
emit_byte(pstate, (uint8_t)tok);
}
#define BINOP_STACK_FRAME_SIZE 16
#define STACK_LIMIT 8192
// Intentionally left as macro rather than a function, to let the
// compiler to inline calls and mimimize runtime stack usage.
#define PARSE_LTR_BINOP(p, f1, f2, ops, prev_op) \
do { \
mjs_err_t res = MJS_OK; \
p->depth++; \
if(p->depth > (STACK_LIMIT / BINOP_STACK_FRAME_SIZE)) { \
mjs_set_errorf(p->mjs, MJS_SYNTAX_ERROR, "parser stack overflow"); \
res = MJS_SYNTAX_ERROR; \
goto binop_clean; \
} \
if((res = f1(p, TOK_EOF)) != MJS_OK) goto binop_clean; \
if(prev_op != TOK_EOF) emit_op(p, prev_op); \
if(findtok(ops, p->tok.tok) != TOK_EOF) { \
int op = p->tok.tok; \
size_t off_if = 0; \
/* For AND/OR, implement short-circuit evaluation */ \
if(ops[0] == TOK_LOGICAL_AND || ops[0] == TOK_LOGICAL_OR) { \
emit_byte( \
p, \
(uint8_t)(ops[0] == TOK_LOGICAL_AND ? OP_JMP_NEUTRAL_FALSE : \
OP_JMP_NEUTRAL_TRUE)); \
off_if = p->cur_idx; \
emit_init_offset(p); \
/* No need to emit TOK_LOGICAL_AND and TOK_LOGICAL_OR: */ \
/* Just drop the first value, and evaluate the second one. */ \
emit_byte(p, (uint8_t)OP_DROP); \
op = TOK_EOF; \
} \
pnext1(p); \
if((res = f2(p, op)) != MJS_OK) goto binop_clean; \
\
if(off_if != 0) { \
mjs_bcode_insert_offset( \
p, p->mjs, off_if, p->cur_idx - off_if - MJS_INIT_OFFSET_SIZE); \
} \
} \
binop_clean: \
p->depth--; \
return res; \
} while(0)
#define PARSE_RTL_BINOP(p, f1, f2, ops, prev_op) \
do { \
mjs_err_t res = MJS_OK; \
(void)prev_op; \
if((res = f1(p, TOK_EOF)) != MJS_OK) return res; \
if(findtok(ops, p->tok.tok) != TOK_EOF) { \
int op = p->tok.tok; \
pnext1(p); \
if((res = f2(p, TOK_EOF)) != MJS_OK) return res; \
emit_op(p, op); \
} \
return res; \
} while(0)
#if MJS_INIT_OFFSET_SIZE > 0
static void emit_init_offset(struct pstate* p) {
size_t i;
for(i = 0; i < MJS_INIT_OFFSET_SIZE; i++) {
emit_byte(p, 0);
}
}
#else
static void emit_init_offset(struct pstate* p) {
(void)p;
}
#endif
static mjs_err_t parse_statement_list(struct pstate* p, int et) {
mjs_err_t res = MJS_OK;
int drop = 0;
pnext1(p);
while(res == MJS_OK && p->tok.tok != TOK_EOF && p->tok.tok != et) {
if(drop) emit_byte(p, OP_DROP);
res = parse_statement(p);
drop = 1;
while(p->tok.tok == TOK_SEMICOLON)
pnext1(p);
}
/*
* Client code expects statement list to contain a value, so if the statement
* list was empty, push `undefined`.
*/
if(!drop) {
emit_byte(p, OP_PUSH_UNDEF);
}
return res;
}
static mjs_err_t parse_block(struct pstate* p, int mkscope) {
mjs_err_t res = MJS_OK;
p->depth++;
if(p->depth > (STACK_LIMIT / BINOP_STACK_FRAME_SIZE)) {
mjs_set_errorf(p->mjs, MJS_SYNTAX_ERROR, "parser stack overflow");
res = MJS_SYNTAX_ERROR;
return res;
}
LOG(LL_VERBOSE_DEBUG, ("[%.*s]", 10, p->tok.ptr));
if(mkscope) emit_byte(p, OP_NEW_SCOPE);
res = parse_statement_list(p, TOK_CLOSE_CURLY);
EXPECT(p, TOK_CLOSE_CURLY);
if(mkscope) emit_byte(p, OP_DEL_SCOPE);
return res;
}
static mjs_err_t parse_function(struct pstate* p) {
size_t prologue, off;
int arg_no = 0;
int name_provided = 0;
mjs_err_t res = MJS_OK;
EXPECT(p, TOK_KEYWORD_FUNCTION);
if(p->tok.tok == TOK_IDENT) {
/* Function name was provided */
struct tok tmp = p->tok;
name_provided = 1;
emit_byte(p, OP_PUSH_STR);
emit_str(p, tmp.ptr, tmp.len);
emit_byte(p, OP_PUSH_SCOPE);
emit_byte(p, OP_CREATE);
emit_byte(p, OP_PUSH_STR);
emit_str(p, tmp.ptr, tmp.len);
emit_byte(p, OP_FIND_SCOPE);
pnext1(p);
}
emit_byte(p, OP_JMP);
off = p->cur_idx;
emit_init_offset(p);
prologue = p->cur_idx;
EXPECT(p, TOK_OPEN_PAREN);
emit_byte(p, OP_NEW_SCOPE);
// Emit names of function arguments
while(p->tok.tok != TOK_CLOSE_PAREN) {
if(p->tok.tok != TOK_IDENT) SYNTAX_ERROR(p);
emit_byte(p, OP_SET_ARG);
emit_int(p, arg_no);
arg_no++;
emit_str(p, p->tok.ptr, p->tok.len);
if(ptest(p) == TOK_COMMA) pnext1(p);
pnext1(p);
}
EXPECT(p, TOK_CLOSE_PAREN);
if((res = parse_block(p, 0)) != MJS_OK) return res;
emit_byte(p, OP_RETURN);
prologue += mjs_bcode_insert_offset(p, p->mjs, off, p->cur_idx - off - MJS_INIT_OFFSET_SIZE);
emit_byte(p, OP_PUSH_FUNC);
emit_int(p, p->cur_idx - 1 /* OP_PUSH_FUNC */ - prologue);
if(name_provided) {
emit_op(p, TOK_ASSIGN);
}
return res;
}
static mjs_err_t parse_object_literal(struct pstate* p) {
mjs_err_t res = MJS_OK;
EXPECT(p, TOK_OPEN_CURLY);
emit_byte(p, OP_PUSH_OBJ);
while(p->tok.tok != TOK_CLOSE_CURLY) {
if(p->tok.tok != TOK_IDENT && p->tok.tok != TOK_STR) SYNTAX_ERROR(p);
emit_byte(p, OP_DUP);
emit_byte(p, OP_PUSH_STR);
emit_str(p, p->tok.ptr, p->tok.len);
emit_byte(p, OP_SWAP);
pnext1(p);
EXPECT(p, TOK_COLON);
if((res = parse_expr(p)) != MJS_OK) return res;
emit_op(p, TOK_ASSIGN);
emit_byte(p, OP_DROP);
if(p->tok.tok == TOK_COMMA) {
pnext1(p);
} else if(p->tok.tok != TOK_CLOSE_CURLY) {
SYNTAX_ERROR(p);
}
}
return res;
}
static mjs_err_t parse_array_literal(struct pstate* p) {
mjs_err_t res = MJS_OK;
EXPECT(p, TOK_OPEN_BRACKET);
emit_byte(p, OP_PUSH_ARRAY);
while(p->tok.tok != TOK_CLOSE_BRACKET) {
emit_byte(p, OP_DUP);
if((res = parse_expr(p)) != MJS_OK) return res;
emit_byte(p, OP_APPEND);
if(p->tok.tok == TOK_COMMA) pnext1(p);
}
return res;
}
static enum mjs_err parse_literal(struct pstate* p, const struct tok* t) {
struct mbuf* bcode_gen = &p->mjs->bcode_gen;
enum mjs_err res = MJS_OK;
int tok = t->tok;
LOG(LL_VERBOSE_DEBUG, ("[%.*s] %p", p->tok.len, p->tok.ptr, (void*)&t));
switch(t->tok) {
case TOK_KEYWORD_FALSE:
emit_byte(p, OP_PUSH_FALSE);
break;
case TOK_KEYWORD_TRUE:
emit_byte(p, OP_PUSH_TRUE);
break;
case TOK_KEYWORD_UNDEFINED:
emit_byte(p, OP_PUSH_UNDEF);
break;
case TOK_KEYWORD_NULL:
emit_byte(p, OP_PUSH_NULL);
break;
case TOK_IDENT: {
int prev_tok = p->prev_tok;
int next_tok = ptest(p);
emit_byte(p, OP_PUSH_STR);
emit_str(p, t->ptr, t->len);
emit_byte(p, (uint8_t)(prev_tok == TOK_DOT ? OP_SWAP : OP_FIND_SCOPE));
if(!findtok(s_assign_ops, next_tok) && !findtok(s_postfix_ops, next_tok) &&
/* TODO(dfrank): fix: it doesn't work for prefix ops */
!findtok(s_postfix_ops, prev_tok)) {
emit_byte(p, OP_GET);
}
break;
}
case TOK_NUM: {
double iv, d = strtod(t->ptr, NULL);
unsigned long uv = strtoul(t->ptr + 2, NULL, 16);
if(t->ptr[0] == '0' && t->ptr[1] == 'x') d = uv;
if(modf(d, &iv) == 0) {
emit_byte(p, OP_PUSH_INT);
emit_int(p, (int64_t)d);
} else {
emit_byte(p, OP_PUSH_DBL);
emit_str(p, t->ptr, t->len);
}
break;
}
case TOK_STR: {
size_t oldlen;
emit_byte(p, OP_PUSH_STR);
oldlen = bcode_gen->len;
embed_string(bcode_gen, p->cur_idx, t->ptr, t->len, EMBSTR_UNESCAPE);
p->cur_idx += bcode_gen->len - oldlen;
} break;
case TOK_OPEN_BRACKET:
res = parse_array_literal(p);
break;
case TOK_OPEN_CURLY:
res = parse_object_literal(p);
break;
case TOK_OPEN_PAREN:
pnext1(p);
res = parse_expr(p);
if(p->tok.tok != TOK_CLOSE_PAREN) SYNTAX_ERROR(p);
break;
case TOK_KEYWORD_FUNCTION:
res = parse_function(p);
break;
case TOK_KEYWORD_THIS:
emit_byte(p, OP_PUSH_THIS);
break;
default:
SYNTAX_ERROR(p);
}
if(tok != TOK_KEYWORD_FUNCTION) pnext1(p);
return res;
}
static mjs_err_t parse_call_dot_mem(struct pstate* p, int prev_op) {
int ops[] = {TOK_DOT, TOK_OPEN_PAREN, TOK_OPEN_BRACKET, TOK_EOF};
mjs_err_t res = MJS_OK;
if((res = parse_literal(p, &p->tok)) != MJS_OK) return res;
while(findtok(ops, p->tok.tok) != TOK_EOF) {
if(p->tok.tok == TOK_OPEN_BRACKET) {
int prev_tok = p->prev_tok;
EXPECT(p, TOK_OPEN_BRACKET);
if((res = parse_expr(p)) != MJS_OK) return res;
emit_byte(p, OP_SWAP);
EXPECT(p, TOK_CLOSE_BRACKET);
if(!findtok(s_assign_ops, p->tok.tok) && !findtok(s_postfix_ops, p->tok.tok) &&
/* TODO(dfrank): fix: it doesn't work for prefix ops */
!findtok(s_postfix_ops, prev_tok)) {
emit_byte(p, OP_GET);
}
} else if(p->tok.tok == TOK_OPEN_PAREN) {
EXPECT(p, TOK_OPEN_PAREN);
emit_byte(p, OP_ARGS);
while(p->tok.tok != TOK_CLOSE_PAREN) {
if((res = parse_expr(p)) != MJS_OK) return res;
if(p->tok.tok == TOK_COMMA) pnext1(p);
}
emit_byte(p, OP_CALL);
EXPECT(p, TOK_CLOSE_PAREN);
} else if(p->tok.tok == TOK_DOT) {
EXPECT(p, TOK_DOT);
if((res = parse_call_dot_mem(p, TOK_DOT)) != MJS_OK) return res;
}
}
(void)prev_op;
return res;
}
static mjs_err_t parse_postfix(struct pstate* p, int prev_op) {
mjs_err_t res = MJS_OK;
if((res = parse_call_dot_mem(p, prev_op)) != MJS_OK) return res;
if(p->tok.tok == TOK_PLUS_PLUS || p->tok.tok == TOK_MINUS_MINUS) {
int op = p->tok.tok == TOK_PLUS_PLUS ? TOK_POSTFIX_PLUS : TOK_POSTFIX_MINUS;
emit_op(p, op);
pnext1(p);
}
return res;
}
static mjs_err_t parse_unary(struct pstate* p, int prev_op) {
mjs_err_t res = MJS_OK;
int op = TOK_EOF;
if(findtok(s_unary_ops, p->tok.tok) != TOK_EOF) {
op = p->tok.tok;
pnext1(p);
}
if(findtok(s_unary_ops, p->tok.tok) != TOK_EOF) {
res = parse_unary(p, prev_op);
} else {
res = parse_postfix(p, prev_op);
}
if(res != MJS_OK) return res;
if(op != TOK_EOF) {
if(op == TOK_MINUS) op = TOK_UNARY_MINUS;
if(op == TOK_PLUS) op = TOK_UNARY_PLUS;
emit_op(p, op);
}
return res;
}
static mjs_err_t parse_mul_div_rem(struct pstate* p, int prev_op) {
int ops[] = {TOK_MUL, TOK_DIV, TOK_REM, TOK_EOF};
PARSE_LTR_BINOP(p, parse_unary, parse_mul_div_rem, ops, prev_op);
}
static mjs_err_t parse_plus_minus(struct pstate* p, int prev_op) {
int ops[] = {TOK_PLUS, TOK_MINUS, TOK_EOF};
PARSE_LTR_BINOP(p, parse_mul_div_rem, parse_plus_minus, ops, prev_op);
}
static mjs_err_t parse_shifts(struct pstate* p, int prev_op) {
int ops[] = {TOK_LSHIFT, TOK_RSHIFT, TOK_URSHIFT, TOK_EOF};
PARSE_LTR_BINOP(p, parse_plus_minus, parse_shifts, ops, prev_op);
}
static mjs_err_t parse_comparison(struct pstate* p, int prev_op) {
PARSE_LTR_BINOP(p, parse_shifts, parse_comparison, s_comparison_ops, prev_op);
}
static mjs_err_t parse_equality(struct pstate* p, int prev_op) {
PARSE_LTR_BINOP(p, parse_comparison, parse_equality, s_equality_ops, prev_op);
}
static mjs_err_t parse_bitwise_and(struct pstate* p, int prev_op) {
int ops[] = {TOK_AND, TOK_EOF};
PARSE_LTR_BINOP(p, parse_equality, parse_bitwise_and, ops, prev_op);
}
static mjs_err_t parse_bitwise_xor(struct pstate* p, int prev_op) {
int ops[] = {TOK_XOR, TOK_EOF};
PARSE_LTR_BINOP(p, parse_bitwise_and, parse_bitwise_xor, ops, prev_op);
}
static mjs_err_t parse_bitwise_or(struct pstate* p, int prev_op) {
int ops[] = {TOK_OR, TOK_EOF};
PARSE_LTR_BINOP(p, parse_bitwise_xor, parse_bitwise_or, ops, prev_op);
}
static mjs_err_t parse_logical_and(struct pstate* p, int prev_op) {
int ops[] = {TOK_LOGICAL_AND, TOK_EOF};
PARSE_LTR_BINOP(p, parse_bitwise_or, parse_logical_and, ops, prev_op);
}
static mjs_err_t parse_logical_or(struct pstate* p, int prev_op) {
int ops[] = {TOK_LOGICAL_OR, TOK_EOF};
PARSE_LTR_BINOP(p, parse_logical_and, parse_logical_or, ops, prev_op);
}
static mjs_err_t parse_ternary(struct pstate* p, int prev_op) {
mjs_err_t res = MJS_OK;
if((res = parse_logical_or(p, TOK_EOF)) != MJS_OK) return res;
if(prev_op != TOK_EOF) emit_op(p, prev_op);
if(p->tok.tok == TOK_QUESTION) {
size_t off_if, off_endif, off_else;
EXPECT(p, TOK_QUESTION);
emit_byte(p, OP_JMP_FALSE);
off_if = p->cur_idx;
emit_init_offset(p);
if((res = parse_ternary(p, TOK_EOF)) != MJS_OK) return res;
emit_byte(p, OP_JMP);
off_else = p->cur_idx;
emit_init_offset(p);
off_endif = p->cur_idx;
emit_byte(p, OP_DROP);
EXPECT(p, TOK_COLON);
if((res = parse_ternary(p, TOK_EOF)) != MJS_OK) return res;
/*
* NOTE: if inserting offset causes the code to move, off_endif needs to be
* adjusted
*/
off_endif += mjs_bcode_insert_offset(
p, p->mjs, off_else, p->cur_idx - off_else - MJS_INIT_OFFSET_SIZE);
mjs_bcode_insert_offset(p, p->mjs, off_if, off_endif - off_if - MJS_INIT_OFFSET_SIZE);
}
return res;
}
static mjs_err_t parse_assignment(struct pstate* p, int prev_op) {
PARSE_RTL_BINOP(p, parse_ternary, parse_assignment, s_assign_ops, prev_op);
}
static mjs_err_t parse_expr(struct pstate* p) {
return parse_assignment(p, TOK_EOF);
}
static mjs_err_t parse_let(struct pstate* p) {
mjs_err_t res = MJS_OK;
LOG(LL_VERBOSE_DEBUG, ("[%.*s]", 10, p->tok.ptr));
if((p)->tok.tok != TOK_KEYWORD_VAR && (p)->tok.tok != TOK_KEYWORD_LET &&
(p)->tok.tok != TOK_KEYWORD_CONST)
SYNTAX_ERROR(p);
else
pnext1(p);
for(;;) {
struct tok tmp = p->tok;
EXPECT(p, TOK_IDENT);
emit_byte(p, OP_PUSH_STR);
emit_str(p, tmp.ptr, tmp.len);
emit_byte(p, OP_PUSH_SCOPE);
emit_byte(p, OP_CREATE);
if(p->tok.tok == TOK_ASSIGN) {
pnext1(p);
emit_byte(p, OP_PUSH_STR);
emit_str(p, tmp.ptr, tmp.len);
emit_byte(p, OP_FIND_SCOPE);
if((res = parse_expr(p)) != MJS_OK) return res;
emit_op(p, TOK_ASSIGN);
} else {
emit_byte(p, OP_PUSH_UNDEF);
}
if(p->tok.tok == TOK_COMMA) {
emit_byte(p, OP_DROP);
pnext1(p);
}
if(p->tok.tok == TOK_SEMICOLON || p->tok.tok == TOK_EOF) break;
}
return res;
}
static mjs_err_t parse_block_or_stmt(struct pstate* p, int cs) {
if(ptest(p) == TOK_OPEN_CURLY) {
return parse_block(p, cs);
} else {
return parse_statement(p);
}
}
static mjs_err_t parse_for_in(struct pstate* p) {
mjs_err_t res = MJS_OK;
size_t off_b, off_check_end;
/* new scope should be pushed before OP_LOOP instruction */
emit_byte(p, OP_NEW_SCOPE);
/* Put iterator variable name to the stack */
if(p->tok.tok == TOK_KEYWORD_LET) {
EXPECT(p, TOK_KEYWORD_LET);
emit_byte(p, OP_PUSH_STR);
emit_str(p, p->tok.ptr, p->tok.len);
emit_byte(p, OP_PUSH_SCOPE);
emit_byte(p, OP_CREATE);
}
emit_byte(p, OP_PUSH_STR);
emit_str(p, p->tok.ptr, p->tok.len);
/* Put object to the stack */
EXPECT(p, TOK_IDENT);
EXPECT(p, TOK_KEYWORD_IN);
parse_expr(p);
EXPECT(p, TOK_CLOSE_PAREN);
emit_byte(p, OP_PUSH_UNDEF); /* Push iterator */
/* Before parsing condition statement, push break/continue offsets */
emit_byte(p, OP_LOOP);
off_b = p->cur_idx;
emit_init_offset(p);
emit_byte(p, 0); /* Point OP_CONTINUE to the next instruction */
emit_byte(p, OP_FOR_IN_NEXT);
emit_byte(p, OP_DUP);
emit_byte(p, OP_JMP_FALSE);
off_check_end = p->cur_idx;
emit_init_offset(p);
// Parse loop body
if(p->tok.tok == TOK_OPEN_CURLY) {
if((res = parse_statement_list(p, TOK_CLOSE_CURLY)) != MJS_OK) return res;
pnext1(p);
} else {
if((res = parse_statement(p)) != MJS_OK) return res;
}
emit_byte(p, OP_DROP);
emit_byte(p, OP_CONTINUE);
/* jump cond -> break */
mjs_bcode_insert_offset(
p, p->mjs, off_check_end, p->cur_idx - off_check_end - MJS_INIT_OFFSET_SIZE);
/* NOTE: jump C -> cond link is already established, it's constant: zero */
emit_byte(p, OP_BREAK);
/* jump B -> cond */
mjs_bcode_insert_offset(p, p->mjs, off_b, p->cur_idx - off_b - MJS_INIT_OFFSET_SIZE);
emit_byte(p, OP_DROP);
emit_byte(p, OP_DROP);
emit_byte(p, OP_DROP);
emit_byte(p, OP_DEL_SCOPE);
return res;
}
static int check_for_in(struct pstate* p) {
struct pstate saved = *p;
int forin = 0;
if(p->tok.tok == TOK_KEYWORD_LET) pnext1(p);
if(p->tok.tok == TOK_IDENT) {
pnext1(p);
if(p->tok.tok == TOK_KEYWORD_IN) forin = 1;
}
*p = saved;
return forin;
}
static mjs_err_t parse_for(struct pstate* p) {
mjs_err_t res = MJS_OK;
size_t off_b, off_c, off_init_end;
size_t off_incr_begin, off_cond_begin, off_cond_end;
int buf_cur_idx;
LOG(LL_VERBOSE_DEBUG, ("[%.*s]", 10, p->tok.ptr));
EXPECT(p, TOK_KEYWORD_FOR);
EXPECT(p, TOK_OPEN_PAREN);
/* Look forward - is it for..in ? */
if(check_for_in(p)) return parse_for_in(p);
/*
* BC is a break+continue offsets (a part of OP_LOOP opcode)
*
* BC init incr cond body break del_scope
* || | ^ ^ | ^ ^
* || +--|-----+ | | |
* |+-------+ +--------+ |
* +---------------------------------+
*
* The order to setup links:
*
* cond -> break
* init -> cond
* C -> incr
* B -> del_scope
*/
/* new scope should be pushed before OP_LOOP instruction */
emit_byte(p, OP_NEW_SCOPE);
/* Before parsing condition statement, push break/continue offsets */
emit_byte(p, OP_LOOP);
off_b = p->cur_idx;
emit_init_offset(p);
off_c = p->cur_idx;
emit_init_offset(p);
/* Parse init statement */
if(p->tok.tok == TOK_KEYWORD_LET) {
if((res = parse_let(p)) != MJS_OK) return res;
} else {
if((res = parse_expr(p)) != MJS_OK) return res;
}
EXPECT(p, TOK_SEMICOLON);
emit_byte(p, OP_DROP);
emit_byte(p, OP_JMP);
off_init_end = p->cur_idx;
emit_init_offset(p);
off_incr_begin = p->cur_idx;
off_cond_begin = p->cur_idx;
/* Parse cond statement */
if((res = parse_expr(p)) != MJS_OK) return res;
EXPECT(p, TOK_SEMICOLON);
/* Parse incr statement */
/* Incr statement should be placed before cond, so, adjust cur_idx */
buf_cur_idx = p->cur_idx;
p->cur_idx = off_incr_begin;
if((res = parse_expr(p)) != MJS_OK) return res;
EXPECT(p, TOK_CLOSE_PAREN);
emit_byte(p, OP_DROP);
/*
* Now incr is inserted before cond, so we adjust cur_idx back, and set
* off_cond_begin to the correct value
*/
{
int incr_size = p->cur_idx - off_incr_begin;
off_cond_begin += incr_size;
p->cur_idx = buf_cur_idx + incr_size;
}
/* p->cur_idx is now at the end of "cond" */
/* Exit the loop if false */
emit_byte(p, OP_JMP_FALSE);
off_cond_end = p->cur_idx;
emit_init_offset(p);
/* Parse loop body */
if(p->tok.tok == TOK_OPEN_CURLY) {
if((res = parse_statement_list(p, TOK_CLOSE_CURLY)) != MJS_OK) return res;
pnext1(p);
} else {
if((res = parse_statement(p)) != MJS_OK) return res;
}
emit_byte(p, OP_DROP);
emit_byte(p, OP_CONTINUE);
/* p->cur_idx is at the "break" item now */
/* jump cond -> break */
mjs_bcode_insert_offset(
p, p->mjs, off_cond_end, p->cur_idx - off_cond_end - MJS_INIT_OFFSET_SIZE);
/* jump init -> cond (and adjust off_incr_begin which may move) */
off_incr_begin += mjs_bcode_insert_offset(
p, p->mjs, off_init_end, off_cond_begin - off_init_end - MJS_INIT_OFFSET_SIZE);
/* jump C -> incr */
mjs_bcode_insert_offset(p, p->mjs, off_c, off_incr_begin - off_c - MJS_INIT_OFFSET_SIZE);
emit_byte(p, OP_BREAK);
/* jump B -> del_scope */
mjs_bcode_insert_offset(p, p->mjs, off_b, p->cur_idx - off_b - MJS_INIT_OFFSET_SIZE);
emit_byte(p, OP_DEL_SCOPE);
return res;
}
static mjs_err_t parse_while(struct pstate* p) {
size_t off_cond_end, off_b;
mjs_err_t res = MJS_OK;
EXPECT(p, TOK_KEYWORD_WHILE);
EXPECT(p, TOK_OPEN_PAREN);
/* new scope should be pushed before OP_LOOP instruction */
emit_byte(p, OP_NEW_SCOPE);
/*
* BC is a break+continue offsets (a part of OP_LOOP opcode)
*
* BC cond body break del_scope
* || ^ | ^ ^
* || | | | |
* |+-+ +------+ |
* +------------------+
*
* The order to setup links:
*
* cond -> break
* C -> cond
* B -> del_scope
*/
emit_byte(p, OP_LOOP);
off_b = p->cur_idx;
emit_init_offset(p);
emit_byte(p, 0); /* Point OP_CONTINUE to the next instruction */
// parse condition statement
if((res = parse_expr(p)) != MJS_OK) return res;
EXPECT(p, TOK_CLOSE_PAREN);
// Exit the loop if false
emit_byte(p, OP_JMP_FALSE);
off_cond_end = p->cur_idx;
emit_init_offset(p);
// Parse loop body
if(p->tok.tok == TOK_OPEN_CURLY) {
if((res = parse_statement_list(p, TOK_CLOSE_CURLY)) != MJS_OK) return res;
pnext1(p);
} else {
if((res = parse_statement(p)) != MJS_OK) return res;
}
emit_byte(p, OP_DROP);
emit_byte(p, OP_CONTINUE);
/* jump cond -> break */
mjs_bcode_insert_offset(
p, p->mjs, off_cond_end, p->cur_idx - off_cond_end - MJS_INIT_OFFSET_SIZE);
/* NOTE: jump C -> cond link is already established, it's constant: zero */
emit_byte(p, OP_BREAK);
/* jump B -> cond */
mjs_bcode_insert_offset(p, p->mjs, off_b, p->cur_idx - off_b - MJS_INIT_OFFSET_SIZE);
emit_byte(p, OP_DEL_SCOPE);
return res;
}
static mjs_err_t parse_if(struct pstate* p) {
size_t off_if, off_endif;
mjs_err_t res = MJS_OK;
LOG(LL_VERBOSE_DEBUG, ("[%.*s]", 10, p->tok.ptr));
EXPECT(p, TOK_KEYWORD_IF);
EXPECT(p, TOK_OPEN_PAREN);
if((res = parse_expr(p)) != MJS_OK) return res;
emit_byte(p, OP_JMP_FALSE);
off_if = p->cur_idx;
emit_init_offset(p);
EXPECT(p, TOK_CLOSE_PAREN);
if((res = parse_block_or_stmt(p, 1)) != MJS_OK) return res;
if(p->tok.tok == TOK_KEYWORD_ELSE) {
/*
* Else clause is present, so, if the condition is not true, the jump
* target (off_endif) should be not the current offset, but the offset
* after jump-over-else opcode
*/
size_t off_else, off_endelse;
pnext1(p);
emit_byte(p, OP_JMP);
off_else = p->cur_idx;
emit_init_offset(p);
off_endif = p->cur_idx;
emit_byte(p, OP_DROP);
if((res = parse_block_or_stmt(p, 1)) != MJS_OK) return res;
off_endelse = p->cur_idx;
/*
* NOTE: if inserting offset causes the code to move, off_endif needs to be
* adjusted
*/
off_endif += mjs_bcode_insert_offset(
p, p->mjs, off_else, off_endelse - off_else - MJS_INIT_OFFSET_SIZE);
} else {
/* Else clause is not present, so, current offset is a jump target
* (off_endif) */
off_endif = p->cur_idx;
}
mjs_bcode_insert_offset(p, p->mjs, off_if, off_endif - off_if - MJS_INIT_OFFSET_SIZE);
return res;
}
static void pstate_revert(struct pstate* p, struct pstate* old, int old_bcode_gen_len) {
p->pos = old->pos;
p->line_no = old->line_no;
p->last_emitted_line_no = old->last_emitted_line_no;
p->offset_lineno_map.len = old->offset_lineno_map.len;
p->prev_tok = old->prev_tok;
p->tok = old->tok;
p->mjs->bcode_gen.len = old_bcode_gen_len;
p->cur_idx = old->cur_idx;
p->depth = old->depth;
}
static mjs_err_t parse_return(struct pstate* p) {
int old_bcode_gen_len;
struct pstate p_saved;
EXPECT(p, TOK_KEYWORD_RETURN);
p_saved = *p;
old_bcode_gen_len = p->mjs->bcode_gen.len;
if(parse_expr(p) != MJS_OK) {
/*
* Failed to parse an expression to return, so return the parser to the
* prior state and push undefined.
*/
pstate_revert(p, &p_saved, old_bcode_gen_len);
emit_byte(p, OP_PUSH_UNDEF);
}
emit_byte(p, OP_SETRETVAL);
emit_byte(p, OP_RETURN);
return MJS_OK;
}
static mjs_err_t parse_statement(struct pstate* p) {
LOG(LL_VERBOSE_DEBUG, ("[%.*s]", 10, p->tok.ptr));
switch(p->tok.tok) {
case TOK_SEMICOLON:
emit_byte(p, OP_PUSH_UNDEF);
pnext1(p);
return MJS_OK;
case TOK_KEYWORD_LET:
case TOK_KEYWORD_VAR:
case TOK_KEYWORD_CONST:
return parse_let(p);
case TOK_OPEN_CURLY:
return parse_block(p, 1);
case TOK_KEYWORD_RETURN:
return parse_return(p);
case TOK_KEYWORD_FOR:
return parse_for(p);
case TOK_KEYWORD_WHILE:
return parse_while(p);
case TOK_KEYWORD_BREAK:
emit_byte(p, OP_PUSH_UNDEF);
emit_byte(p, OP_BREAK);
pnext1(p);
return MJS_OK;
case TOK_KEYWORD_CONTINUE:
emit_byte(p, OP_CONTINUE);
pnext1(p);
return MJS_OK;
case TOK_KEYWORD_IF:
return parse_if(p);
case TOK_KEYWORD_CASE:
case TOK_KEYWORD_CATCH:
case TOK_KEYWORD_DELETE:
case TOK_KEYWORD_DO:
case TOK_KEYWORD_INSTANCEOF:
case TOK_KEYWORD_NEW:
case TOK_KEYWORD_SWITCH:
case TOK_KEYWORD_THROW:
case TOK_KEYWORD_TRY:
case TOK_KEYWORD_VOID:
case TOK_KEYWORD_WITH:
mjs_set_errorf(
p->mjs, MJS_SYNTAX_ERROR, "[%.*s] is not implemented", p->tok.len, p->tok.ptr);
return MJS_SYNTAX_ERROR;
default: {
mjs_err_t res = MJS_OK;
for(;;) {
if((res = parse_expr(p)) != MJS_OK) return res;
if(p->tok.tok != TOK_COMMA) break;
emit_byte(p, OP_DROP);
pnext1(p);
}
return res;
}
}
}
MJS_PRIVATE mjs_err_t mjs_parse(const char* path, const char* buf, struct mjs* mjs) {
mjs_err_t res = MJS_OK;
struct pstate p;
size_t start_idx, llen;
int map_len;
mjs_header_item_t bcode_offset, map_offset, total_size;
pinit(path, buf, &p);
p.mjs = mjs;
p.cur_idx = p.mjs->bcode_gen.len;
emit_byte(&p, OP_BCODE_HEADER);
/*
* TODO(dfrank): don't access mjs->bcode_gen directly, use emit_... API which
* takes care of p->cur_idx
*/
/* Remember starting bcode position, and reserve the room for bcode header */
start_idx = p.mjs->bcode_gen.len;
mbuf_append(&p.mjs->bcode_gen, NULL, sizeof(mjs_header_item_t) * MJS_HDR_ITEMS_CNT);
/* Append NULL-terminated filename */
mbuf_append(&p.mjs->bcode_gen, path, strlen(path) + 1 /* null-terminate */);
bcode_offset = p.mjs->bcode_gen.len - start_idx;
memcpy(
p.mjs->bcode_gen.buf + start_idx + sizeof(mjs_header_item_t) * MJS_HDR_ITEM_BCODE_OFFSET,
&bcode_offset,
sizeof(mjs_header_item_t));
p.start_bcode_idx = p.mjs->bcode_gen.len;
p.cur_idx = p.mjs->bcode_gen.len;
res = parse_statement_list(&p, TOK_EOF);
emit_byte(&p, OP_EXIT);
/* remember map offset */
map_offset = p.mjs->bcode_gen.len - start_idx;
memcpy(
p.mjs->bcode_gen.buf + start_idx + sizeof(mjs_header_item_t) * MJS_HDR_ITEM_MAP_OFFSET,
&map_offset,
sizeof(mjs_header_item_t));
/* put map length varint */
map_len = p.offset_lineno_map.len;
llen = cs_varint_llen(map_len);
mbuf_resize(&p.mjs->bcode_gen, p.mjs->bcode_gen.size + llen);
cs_varint_encode(map_len, (uint8_t*)p.mjs->bcode_gen.buf + p.mjs->bcode_gen.len, llen);
p.mjs->bcode_gen.len += llen;
/* put the map itself */
mbuf_append(&p.mjs->bcode_gen, p.offset_lineno_map.buf, p.offset_lineno_map.len);
total_size = p.mjs->bcode_gen.len - start_idx;
memcpy(
p.mjs->bcode_gen.buf + start_idx + sizeof(mjs_header_item_t) * MJS_HDR_ITEM_TOTAL_SIZE,
&total_size,
sizeof(mjs_header_item_t));
mbuf_free(&p.offset_lineno_map);
/*
* If parsing was successful, commit the bcode; otherwise drop generated
* bcode
*/
if(res == MJS_OK) {
mjs_bcode_commit(mjs);
} else {
mbuf_free(&mjs->bcode_gen);
}
return res;
}
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