mrsh/parser/arithm.c -rw-r--r-- 10.9 KiB View raw
                                                                                
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#define _POSIX_C_SOURCE 200809L
#include <ctype.h>
#include <errno.h>
#include <mrsh/arithm.h>
#include <stdlib.h>
#include <string.h>
#include "parser.h"

static bool parse_char(struct mrsh_parser *state, char c) {
18 references
if (parser_peek_char(state) != c) { return false; } parser_read_char(state); return true; } static bool parse_whitespace(struct mrsh_parser *state) {
1 reference
if (!isspace(parser_peek_char(state))) { return false; } parser_read_char(state); return true; } static inline void consume_whitespace(struct mrsh_parser *state) {
8 references
while (parse_whitespace(state)) { // This space is intentionally left blank } } static bool expect_char(struct mrsh_parser *state, char c) {
2 references
if (parse_char(state, c)) { return true; } char msg[128]; snprintf(msg, sizeof(msg), "expected '%c'", c); parser_set_error(state, msg); return false; } static bool parse_str(struct mrsh_parser *state, const char *str) {
9 references
size_t len = strlen(str); for (size_t i = 0; i < len; ++i) { parser_peek(state, NULL, i + 1); if (state->buf.data[i] != str[i]) { return false; } } parser_read(state, NULL, len); return true; } static size_t peek_literal(struct mrsh_parser *state) {
1 reference
size_t i = 0; while (true) { parser_peek(state, NULL, i + 1); char c = state->buf.data[i]; // TODO: 0x, 0b prefixes if (!isdigit(c)) { break; } ++i; } return i; } static struct mrsh_arithm_literal *literal(struct mrsh_parser *state) {
1 reference
size_t len = peek_literal(state); if (len == 0) { return NULL; } char *str = strndup(state->buf.data, len); parser_read(state, NULL, len); char *end; errno = 0; long value = strtol(str, &end, 0); if (end[0] != '\0' || errno != 0) { free(str); parser_set_error(state, "failed to parse literal"); return NULL; } free(str); return mrsh_arithm_literal_create(value); } static struct mrsh_arithm_expr *arithm_expr(struct mrsh_parser *state); static struct mrsh_arithm_unop *unop(struct mrsh_parser *state) {
1 reference
enum mrsh_arithm_unop_type type; switch (parser_peek_char(state)) { case '+': type = MRSH_ARITHM_UNOP_PLUS; break; case '-': type = MRSH_ARITHM_UNOP_MINUS; break; case '~': type = MRSH_ARITHM_UNOP_TILDE; break; case '!': type = MRSH_ARITHM_UNOP_BANG; break; default: return NULL; } parser_read_char(state); struct mrsh_arithm_expr *body = arithm_expr(state); if (body == NULL) { parser_set_error(state, "expected an arithmetic expression after unary operator"); return NULL; } return mrsh_arithm_unop_create(type, body); } static struct mrsh_arithm_expr *paren(struct mrsh_parser *state) {
1 reference
if (!parse_char(state, '(')) { return NULL; } consume_whitespace(state); struct mrsh_arithm_expr *expr = arithm_expr(state); // consume_whitespace() is not needed here, since the call to arithm_expr() // consumes the trailing whitespace. if (!expect_char(state, ')')) { mrsh_arithm_expr_destroy(expr); return NULL; } return expr; } static struct mrsh_arithm_expr *term(struct mrsh_parser *state) {
4 references
struct mrsh_arithm_expr *expr = paren(state); if (expr != NULL) { return expr; } struct mrsh_arithm_unop *au = unop(state); if (au != NULL) { return &au->expr; } struct mrsh_arithm_literal *al = literal(state); if (al != NULL) { return &al->expr; } return NULL; } static struct mrsh_arithm_expr *factor(struct mrsh_parser *state) { struct mrsh_arithm_expr *left = term(state); if (left == NULL) { return NULL; } consume_whitespace(state); enum mrsh_arithm_binop_type type; if (parse_char(state, '*')) { type = MRSH_ARITHM_BINOP_ASTERISK; } else if (parse_char(state, '/')) { type = MRSH_ARITHM_BINOP_SLASH; } else if (parse_char(state, '%')) { type = MRSH_ARITHM_BINOP_PERCENT; } else { return left; } consume_whitespace(state); struct mrsh_arithm_expr *right = factor(state); if (right == NULL) { parser_set_error(state, "expected a term after *, / or % operator"); return NULL; } struct mrsh_arithm_binop *bo = mrsh_arithm_binop_create(type, left, right); return &bo->expr; } static struct mrsh_arithm_expr *addend(struct mrsh_parser *state) { struct mrsh_arithm_expr *left = factor(state); if (left == NULL) { return NULL; } // consume_whitespace() is not needed here, since the call to factor() // consumes trailing whitespace. enum mrsh_arithm_binop_type type; if (parse_char(state, '+')) { type = MRSH_ARITHM_BINOP_PLUS; } else if (parse_char(state, '-')) { type = MRSH_ARITHM_BINOP_MINUS; } else { return left; } consume_whitespace(state); struct mrsh_arithm_expr *right = addend(state); if (right == NULL) { parser_set_error(state, "expected a factor after + or - operator"); return NULL; } struct mrsh_arithm_binop *bo = mrsh_arithm_binop_create(type, left, right); return &bo->expr; } static struct mrsh_arithm_expr *shift(struct mrsh_parser *state) { struct mrsh_arithm_expr *left = addend(state); if (left == NULL) { return NULL; } // consume_whitespace() is not needed here, since the call to addend() // consumes the trailing whitespace. enum mrsh_arithm_binop_type type; if (parse_str(state, "<<")) { type = MRSH_ARITHM_BINOP_DLESS; } else if (parse_str(state, ">>")) { type = MRSH_ARITHM_BINOP_DGREAT; } else { return left; } consume_whitespace(state); struct mrsh_arithm_expr *right = shift(state); if (right == NULL) { mrsh_arithm_expr_destroy(left); parser_set_error(state, "expected a term"); return NULL; } struct mrsh_arithm_binop *bo = mrsh_arithm_binop_create(type, left, right); return &bo->expr; } static struct mrsh_arithm_expr *comp(struct mrsh_parser *state) { struct mrsh_arithm_expr *left = shift(state); if (left == NULL) { return NULL; } enum mrsh_arithm_binop_type type; if (parse_char(state, '<')) { type = MRSH_ARITHM_BINOP_LESS; } else if (parse_str(state, "<=")) { type = MRSH_ARITHM_BINOP_LESSEQ; } else if (parse_char(state, '>')) { type = MRSH_ARITHM_BINOP_GREAT; } else if (parse_str(state, ">=")) { type = MRSH_ARITHM_BINOP_GREATEQ; } else { return left; } consume_whitespace(state); struct mrsh_arithm_expr *right = comp(state); if (left == NULL) { mrsh_arithm_expr_destroy(left); parser_set_error(state, "expected a term"); return NULL; } struct mrsh_arithm_binop *bo = mrsh_arithm_binop_create(type, left, right); return &bo->expr; } static struct mrsh_arithm_expr *equal(struct mrsh_parser *state) { struct mrsh_arithm_expr *left = comp(state); if (left == NULL) { return NULL; } enum mrsh_arithm_binop_type type; if (parse_str(state, "==")) { type = MRSH_ARITHM_BINOP_DEQ; } else if (parse_str(state, "!=")) { type = MRSH_ARITHM_BINOP_BANGEQ; } else { return left; } struct mrsh_arithm_expr *right = equal(state); if (left == NULL) { mrsh_arithm_expr_destroy(left); parser_set_error(state, "expected a term"); return NULL; } struct mrsh_arithm_binop *bo = mrsh_arithm_binop_create(type, left, right); return &bo->expr; } static struct mrsh_arithm_expr *binop(struct mrsh_parser *state, enum mrsh_arithm_binop_type type, const char *str, struct mrsh_arithm_expr *(*term)(struct mrsh_parser *state)) { struct mrsh_arithm_expr *left = term(state); if (left == NULL) { return NULL; } if (!parse_str(state, str)) { return left; } consume_whitespace(state); struct mrsh_arithm_expr *right = binop(state, type, str, term); if (left == NULL) { mrsh_arithm_expr_destroy(left); parser_set_error(state, "expected a term"); return NULL; } struct mrsh_arithm_binop *bo = mrsh_arithm_binop_create(type, left, right); return &bo->expr; } static struct mrsh_arithm_expr *bitwise_and(struct mrsh_parser *state) { return binop(state, MRSH_ARITHM_BINOP_AND, "&", equal); } static struct mrsh_arithm_expr *bitwise_xor(struct mrsh_parser *state) { return binop(state, MRSH_ARITHM_BINOP_CIRC, "^", bitwise_and); } static struct mrsh_arithm_expr *bitwise_or(struct mrsh_parser *state) { return binop(state, MRSH_ARITHM_BINOP_OR, "|", bitwise_xor); } static struct mrsh_arithm_expr *logical_and(struct mrsh_parser *state) { return binop(state, MRSH_ARITHM_BINOP_DAND, "&&", bitwise_or); } static struct mrsh_arithm_expr *logical_or(struct mrsh_parser *state) {
1 reference
return binop(state, MRSH_ARITHM_BINOP_DOR, "||", logical_and); } static struct mrsh_arithm_expr *ternary(struct mrsh_parser *state) { struct mrsh_arithm_expr *expr = logical_or(state); if (expr == NULL) { return NULL; } if (!parse_char(state, '?')) { return expr; } struct mrsh_arithm_expr *condition = expr; struct mrsh_arithm_expr *body = ternary(state); if (body == NULL) { parser_set_error(state, "expected a logical or term"); goto error_body; } if (!expect_char(state, ':')) { goto error_semi; } struct mrsh_arithm_expr *else_part = ternary(state); if (else_part == NULL) { parser_set_error(state, "expected an or term"); goto error_else_part; } struct mrsh_arithm_cond *c = mrsh_arithm_cond_create(condition, body, else_part); return &c->expr; error_else_part: error_semi: mrsh_arithm_expr_destroy(body); error_body: mrsh_arithm_expr_destroy(condition); return NULL; } static struct mrsh_arithm_expr *assignment(struct mrsh_parser *state) {
1 reference
size_t name_len = peek_name(state, false); if (name_len == 0) { return NULL; } parser_peek(state, NULL, name_len + 1); if (state->buf.data[name_len] != '=') { return NULL; } char *name = malloc(name_len + 1); parser_read(state, name, name_len); name[name_len] = '\0'; parser_read(state, NULL, 1); // equal sign enum mrsh_arithm_assign_op op = MRSH_ARITHM_ASSIGN_NONE; if (parse_char(state, '*')) { op = MRSH_ARITHM_ASSIGN_ASTERISK; } else if (parse_char(state, '/')) { op = MRSH_ARITHM_ASSIGN_SLASH; } else if (parse_char(state, '%')) { op = MRSH_ARITHM_ASSIGN_PERCENT; } else if (parse_char(state, '+')) { op = MRSH_ARITHM_ASSIGN_PLUS; } else if (parse_char(state, '-')) { op = MRSH_ARITHM_ASSIGN_MINUS; } else if (parse_str(state, "<<")) { op = MRSH_ARITHM_ASSIGN_DLESS; } else if (parse_str(state, ">>")) { op = MRSH_ARITHM_ASSIGN_DGREAT; } else if (parse_char(state, '&')) { op = MRSH_ARITHM_ASSIGN_AND; } else if (parse_char(state, '^')) { op = MRSH_ARITHM_ASSIGN_CIRC; } else if (parse_char(state, '|')) { op = MRSH_ARITHM_ASSIGN_OR; } struct mrsh_arithm_expr *value = arithm_expr(state); if (value == NULL) { free(name); parser_set_error(state, "expected an assignment value"); return NULL; } struct mrsh_arithm_assign *a = mrsh_arithm_assign_create(op, name, value); return &a->expr; } static struct mrsh_arithm_expr *arithm_expr(struct mrsh_parser *state) { struct mrsh_arithm_expr *expr = assignment(state); if (expr != NULL) { return expr; } return ternary(state); } struct mrsh_arithm_expr *mrsh_parse_arithm_expr(struct mrsh_parser *state) {
1 reference
consume_whitespace(state); struct mrsh_arithm_expr *expr = arithm_expr(state); if (expr == NULL) { return NULL; } if (parser_peek_char(state) != '\0') { parser_set_error(state, "garbage at the end of the arithmetic expression"); mrsh_arithm_expr_destroy(expr); return NULL; } return expr; }