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// FML parser
// Michal Vlasák, FIT CTU, 2023
#include <stdio.h>
#include "parser.h"
#define UNREACHABLE() unreachable(__FILE__, __LINE__)
_Noreturn void
unreachable(char *file, size_t line)
{
fprintf(stderr, "ERROR: unreachable code reached at %s:%zu\n", file, line);
bool str_eq(Str a, Str b)
{
return a.len == b.len && memcmp(a.str, b.str, a.len) == 0;
}
int str_cmp(Str a, Str b)
{
int cmp = memcmp(a.str, b.str, a.len < b.len ? a.len : b.len);
return cmp == 0 ? (a.len > b.len) - (b.len > a.len) : cmp;
}
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typedef struct {
const u8 *pos;
const u8 *end;
} Lexer;
typedef enum {
LS_START,
LS_IDENTIFIER,
LS_NUMBER,
LS_STRING,
LS_STRING_ESC,
LS_SLASH,
LS_LINE_COMMENT,
LS_BLOCK_COMMENT,
LS_BLOCK_COMMENT_STAR,
LS_MINUS,
LS_EQUAL,
LS_GREATER,
LS_LESS,
LS_EXCLAM,
} LexState;
typedef enum {
ASSOC_LEFT,
ASSOC_RIGHT,
} Associativity;
typedef enum {
PREC_NONE,
PREC_EXPR,
PREC_ASGN,
PREC_DISJ,
PREC_CONJ,
PREC_CMP,
PREC_ADD,
PREC_MUL,
PREC_POST,
PREC_TOP,
} Precedence;
#define TOKENS(KW, PU, OT) \
/* token repr nud led prec assoc*/\
OT(NUMBER, "a number", primary, lefterr, TOP, LEFT) \
OT(IDENTIFIER, "an identifier", ident, lefterr, TOP, LEFT) \
OT(STRING, "a string", nullerr, lefterr, TOP, LEFT) \
\
PU(BAR, "|", nullerr, binop, DISJ, LEFT) \
PU(AMPERSANT, "&", nullerr, binop, CONJ, LEFT) \
PU(EQUAL_EQUAL, "==", nullerr, binop, CMP, LEFT) \
PU(BANG_EQUAL, "!=", nullerr, binop, CMP, LEFT) \
PU(GREATER, ">", nullerr, binop, CMP, LEFT) \
PU(LESS, "<", nullerr, binop, CMP, LEFT) \
PU(GREATER_EQUAL, ">=", nullerr, binop, CMP, LEFT) \
PU(LESS_EQUAL, "<=", nullerr, binop, CMP, LEFT) \
PU(PLUS, "+", nullerr, binop, ADD, LEFT) \
PU(MINUS, "-", nullerr, binop, ADD, LEFT) \
PU(ASTERISK, "*", nullerr, binop, MUL, LEFT) \
PU(SLASH, "/", nullerr, binop, MUL, LEFT) \
PU(PERCENT, "%", nullerr, binop, MUL, LEFT) \
\
PU(SEMICOLON, ";", nullerr, stop, NONE, LEFT) \
PU(LPAREN, "(", paren, call, POST, LEFT) \
PU(RPAREN, ")", nullerr, stop, NONE, LEFT) \
PU(EQUAL, "=", nullerr, eqerr, ASGN, LEFT) \
PU(LARROW, "<-", nullerr, assign, ASGN, RIGHT) \
PU(RARROW, "->", nullerr, lefterr, TOP, LEFT) \
PU(DOT, ".", nullerr, field, POST, LEFT) \
PU(LBRACKET, "[", nullerr, indexing, POST, LEFT) \
PU(RBRACKET, "]", nullerr, stop, NONE, LEFT) \
PU(COMMA, ",", nullerr, stop, NONE, LEFT) \
\
KW(BEGIN, "begin", block, stop, NONE, LEFT) \
KW(END, "end", nullerr, stop, NONE, LEFT) \
KW(IF, "if", cond, lefterr, TOP, LEFT) \
KW(THEN, "then", nullerr, stop, NONE, LEFT) \
KW(ELSE, "else", nullerr, stop, NONE, LEFT) \
KW(LET, "let", let, lefterr, TOP, LEFT) \
KW(NULL, "null", primary, lefterr, TOP, LEFT) \
KW(PRINT, "print", print, lefterr, TOP, LEFT) \
KW(OBJECT, "object", object, lefterr, TOP, LEFT) \
KW(EXTENDS, "extends", nullerr, lefterr, TOP, LEFT) \
KW(WHILE, "while", loop, lefterr, TOP, LEFT) \
KW(DO, "do", nullerr, stop, NONE, LEFT) \
KW(FUNCTION, "function", function, lefterr, TOP, LEFT) \
KW(ARRAY, "array", array, lefterr, TOP, LEFT) \
KW(TRUE, "true", primary, lefterr, TOP, LEFT) \
KW(FALSE, "false", primary, lefterr, TOP, LEFT) \
\
OT(EOF, "end of input", nullerr, stop, NONE, LEFT) \
OT(ERROR, "lex error", nullerr, lefterr, TOP, LEFT)
typedef enum {
#define TOK_ENUM(tok, ...) TK_##tok,
TOKENS(TOK_ENUM, TOK_ENUM, TOK_ENUM)
#undef TOK_ENUM
} TokenKind;
static const char *tok_repr[] = {
#define TOK_STR(tok, str, ...) "'"str"'",
#define TOK_STR_OTHER(tok, str, ...) str,
TOKENS(TOK_STR, TOK_STR, TOK_STR_OTHER)
#undef TOK_STR
#undef TOK_STR_OTHER
};
static struct {
const char *str;
TokenKind tok;
} keywords[] = {
#define TOK_KW(tok, str, ...) { str, TK_##tok },
#define TOK_OTHER(tok, str, ...)
TOKENS(TOK_KW, TOK_OTHER, TOK_OTHER)
#undef TOK_KW
#undef TOK_OTHER
};
static bool
tok_is_identifier(TokenKind kind)
{
return kind == TK_IDENTIFIER || (kind >= TK_BAR && kind <= TK_PERCENT);
}
typedef struct {
TokenKind kind;
Str str;
} Token;
Lexer
lex_create(Str source)
{
return (Lexer) {
.pos = source.str,
.end = source.str + source.len,
};
}
#define ALPHA '_': case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g': case 'h': case 'i': case 'j': case 'k': case 'l': case 'm': case 'n': case 'o': case 'p': case 'q': case 'r': case 's': case 't': case 'v': case 'u': case 'w': case 'x': case 'y': case 'z': case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': case 'G': case 'H': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N': case 'O': case 'P': case 'Q': case 'R': case 'S': case 'T': case 'V': case 'U': case 'W': case 'X': case 'Y': case 'Z'
#define DIGIT '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9'
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lex_next(Lexer *lexer, Token *token)
{
LexState state = LS_START;
TokenKind tok = TK_ERROR;
int end_offset = 0;
const u8 *start = lexer->pos;
size_t length;
while (lexer->pos != lexer->end) {
u8 c = *lexer->pos;
switch (state) {
case LS_START: switch (c) {
case ' ': case '\t': case '\n': start += 1; break;
case ALPHA: state = LS_IDENTIFIER; break;
case DIGIT: state = LS_NUMBER; break;
case '"': state = LS_STRING; start += 1; break;
case '/': state = LS_SLASH; break;
case '-': state = LS_MINUS; break;
case '=': state = LS_EQUAL; break;
case '>': state = LS_GREATER; break;
case '<': state = LS_LESS; break;
case '!': state = LS_EXCLAM; break;
case ';': tok = TK_SEMICOLON; goto done;
case '|': tok = TK_BAR; goto done;
case '&': tok = TK_AMPERSANT; goto done;
case '+': tok = TK_PLUS; goto done;
case '*': tok = TK_ASTERISK; goto done;
case '%': tok = TK_PERCENT; goto done;
case '(': tok = TK_LPAREN; goto done;
case ')': tok = TK_RPAREN; goto done;
case '.': tok = TK_DOT; goto done;
case '[': tok = TK_LBRACKET; goto done;
case ']': tok = TK_RBRACKET; goto done;
case ',': tok = TK_COMMA; goto done;
default: tok = TK_ERROR; goto done;
case LS_IDENTIFIER: switch (c) {
case ALPHA: case DIGIT: break;
default: tok = TK_IDENTIFIER; goto prev_done;
case LS_NUMBER: switch (c) {
case DIGIT: break;
default: tok = TK_NUMBER; goto prev_done;
case LS_STRING: switch (c) {
case '"': tok = TK_STRING; end_offset = -1; goto done;
case '\\': state = LS_STRING_ESC; break;
case LS_STRING_ESC: switch (c) {
case 'n': case 't': case 'r': case '~': case '"': case '\\': state = LS_STRING; break;
default: goto err;
case LS_SLASH: switch (c) {
case '/': state = LS_LINE_COMMENT; start += 2; break;
case '*': state = LS_BLOCK_COMMENT; start += 2; break;
default: tok = TK_SLASH; goto prev_done;
case LS_LINE_COMMENT: switch (c) {
case '\n': state = LS_START; start = lexer->pos + 1; break;
case LS_BLOCK_COMMENT: switch (c) {
case '*': state = LS_BLOCK_COMMENT_STAR; break;
case LS_BLOCK_COMMENT_STAR: switch (c) {
case '*': break;
case '/': state = LS_START; start = lexer->pos + 1; break;
default: state = LS_BLOCK_COMMENT; break;
case LS_MINUS: switch (c) {
case '>': tok = TK_RARROW; goto done;
case DIGIT: state = LS_NUMBER; break;
default: tok = TK_MINUS; goto prev_done;
case LS_EQUAL: switch (c) {
case '=': tok = TK_EQUAL_EQUAL; goto done;
default: tok = TK_EQUAL; goto prev_done;
case LS_GREATER: switch (c) {
case '=': tok = TK_GREATER_EQUAL; goto done;
default: tok = TK_GREATER; goto prev_done;
case LS_LESS: switch (c) {
case '=': tok = TK_LESS_EQUAL; goto done;
case '-': tok = TK_LARROW; goto done;
default: tok = TK_LESS; goto prev_done;
case LS_EXCLAM: switch (c) {
case '=': tok = TK_BANG_EQUAL; goto done;
default: goto err;
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}
lexer->pos += 1;
}
switch (state) {
case LS_START: case LS_LINE_COMMENT: tok = TK_EOF; goto prev_done;
case LS_IDENTIFIER: tok = TK_IDENTIFIER; goto prev_done;
case LS_NUMBER: tok = TK_NUMBER; goto prev_done;
case LS_STRING: case LS_STRING_ESC: case LS_BLOCK_COMMENT: case LS_BLOCK_COMMENT_STAR: goto err;
case LS_SLASH: case LS_MINUS: case LS_EQUAL: case LS_GREATER: case LS_LESS: tok = TK_SLASH; goto prev_done;
case LS_EXCLAM: goto err;
}
done:
lexer->pos += 1;
prev_done:
err:
length = lexer->pos - start + end_offset;
if (tok == TK_IDENTIFIER) {
for (size_t i = 0; i < sizeof(keywords) / sizeof(keywords[0]); i++) {
if (strlen(keywords[i].str) == length && memcmp((const char*) start, keywords[i].str, length) == 0) {
tok = keywords[i].tok;
break;
}
}
}
token->kind = tok;
token->str.str = start;
token->str.len = length;
}
typedef struct {
Arena *arena;
GArena *scratch;
void *user_data;
void (*error_callback)(void *user_data, const u8 *err_pos, const char *msg, va_list ap);
Lexer lexer;
Token lookahead;
Token prev;
bool had_error;
bool panic_mode;
} Parser;
static void
parser_error(Parser *parser, Token errtok, bool panic, const char *msg, ...)
{
va_list ap;
va_start(ap, msg);
if (!parser->panic_mode) {
parser->error_callback(parser->user_data, errtok.str.str, msg, ap);
parser->had_error = true;
parser->panic_mode = panic;
}
va_end(ap);
}
static TokenKind
peek(const Parser *parser)
{
return parser->lookahead.kind;
}
static Token
prev_tok(Parser *parser)
{
return parser->prev;
}
static Token
discard(Parser *parser)
{
parser->prev = parser->lookahead;
lex_next(&parser->lexer, &parser->lookahead);
if (parser->lookahead.kind == TK_ERROR) {
parser_error(parser, parser->lookahead, true, "Unexpected character");
}
return parser->prev;
}
static void
eat(Parser *parser, TokenKind kind)
{
TokenKind tok = peek(parser);
if (tok != kind) {
parser_error(parser, parser->lookahead, true, "Expected %s, found %s", tok_repr[kind], tok_repr[tok]);
return;
}
discard(parser);
}
static void
eat_identifier(Parser *parser, Str *identifier)
{
TokenKind tok = peek(parser);
if (!tok_is_identifier(tok)) {
parser_error(parser, parser->lookahead, true, "Expected %s, found %s", tok_repr[TK_IDENTIFIER], tok_repr[tok]);
return;
}
discard(parser);
*identifier = prev_tok(parser).str;
}
static bool
try_eat(Parser *parser, TokenKind kind)
{
if (peek(parser) == kind) {
discard(parser);
return true;
}
return false;
}
#define AST_CREATE(type, var, arena, kind) type *var = ast_create_((arena), (kind), sizeof(type))
static void *
ast_create_(Arena *arena, AstKind kind, size_t size)
{
Ast *ast = arena_alloc(arena, size);
memset(ast, 0, size);
ast->kind = kind;
return ast;
}
static Ast *
create_null(Parser *parser)
{
AST_CREATE(AstNull, ast, parser->arena, AST_NULL);
return &ast->base;
}
static Ast *expression_bp(Parser *parser, int bp);
static Ast *
expression(Parser *parser)
{
return expression_bp(parser, PREC_EXPR);
}
static void
expression_list(Parser *parser, Ast ***list, size_t *n, TokenKind separator, TokenKind terminator)
{
size_t start = garena_save(parser->scratch);
while (!try_eat(parser, terminator)) {
garena_push_value(parser->scratch, Ast *, expression(parser));
if (!try_eat(parser, separator)) {
eat(parser, terminator);
break;
}
}
*n = garena_cnt_from(parser->scratch, start, Ast *);
*list = move_to_arena(parser->arena, parser->scratch, start, Ast *);
}
static void
identifier_list(Parser *parser, Str **list, size_t *n, TokenKind separator, TokenKind terminator)
{
size_t start = garena_save(parser->scratch);
while (!try_eat(parser, terminator)) {
eat_identifier(parser, garena_push(parser->scratch, Str));
if (!try_eat(parser, separator)) {
eat(parser, terminator);
break;
}
}
*n = garena_cnt_from(parser->scratch, start, Str);
*list = move_to_arena(parser->arena, parser->scratch, start, Str);
}
static Ast *
nullerr(Parser *parser)
{
TokenKind tok = peek(parser);
parser_error(parser, parser->lookahead, true, "Invalid start of expression %s", tok_repr[tok]);
return create_null(parser);
}
static Ast *
primary(Parser *parser)
{
Token token = discard(parser);
switch (token.kind) {
case TK_NUMBER: {
AST_CREATE(AstInteger, integer, parser->arena, AST_INTEGER);
const u8 *pos = token.str.str;
const u8 *end = pos + token.str.len;
bool negative = 0;
while (*pos == '-') {
negative = !negative;
pos += 1;
}
i64 value = 0;
for (; pos < end; pos++) {
value = value * 10 + (*pos - '0');
}
integer->value = (i32) (negative ? -value : value);
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return &integer->base;
}
case TK_NULL: {
AST_CREATE(AstNull, null, parser->arena, AST_NULL);
return &null->base;
}
case TK_TRUE: {
AST_CREATE(AstBoolean, boolean, parser->arena, AST_BOOLEAN);
boolean->value = true;
return &boolean->base;
}
case TK_FALSE: {
AST_CREATE(AstBoolean, boolean, parser->arena, AST_BOOLEAN);
boolean->value = false;
return &boolean->base;
}
default:
UNREACHABLE();
}
}
static Ast *
ident(Parser *parser)
{
AST_CREATE(AstVariableAccess, variable_access, parser->arena, AST_VARIABLE_ACCESS);
eat_identifier(parser, &variable_access->name);
return &variable_access->base;
}
static Ast *
block(Parser *parser)
{
AST_CREATE(AstBlock, block, parser->arena, AST_BLOCK);
eat(parser, TK_BEGIN);
expression_list(parser, &block->expressions, &block->expression_cnt, TK_SEMICOLON, TK_END);
// begin end => null
if (block->expression_cnt == 0) {
block->base.kind = AST_NULL;
}
return &block->base;
}
static Ast *
let(Parser *parser)
{
AST_CREATE(AstDefinition, definition, parser->arena, AST_DEFINITION);
eat(parser, TK_LET);
eat_identifier(parser, &definition->name);
eat(parser, TK_EQUAL);
definition->value = expression(parser);
return &definition->base;
}
static Ast *
array(Parser *parser)
{
AST_CREATE(AstArray, array, parser->arena, AST_ARRAY);
eat(parser, TK_ARRAY);
eat(parser, TK_LPAREN);
array->size = expression(parser);
eat(parser, TK_COMMA);
array->initializer = expression(parser);
eat(parser, TK_RPAREN);
return &array->base;
}
static Ast *
object(Parser *parser)
{
AST_CREATE(AstObject, object, parser->arena, AST_OBJECT);
eat(parser, TK_OBJECT);
Token object_tok = prev_tok(parser);
if (try_eat(parser, TK_EXTENDS)) {
object->extends = expression(parser);
} else {
object->extends = create_null(parser);
}
eat(parser, TK_BEGIN);
expression_list(parser, &object->members, &object->member_cnt, TK_SEMICOLON, TK_END);
for (size_t i = 0; i < object->member_cnt; i++) {
if (object->members[i]->kind != AST_DEFINITION) {
parser_error(parser, object_tok, false, "Found object member that is not a definition");
}
AstDefinition *member = (AstDefinition *) object->members[i];
for (size_t j = 0; j < i; j++) {
AstDefinition *other = (AstDefinition *) object->members[j];
if (str_eq(member->name, other->name)) {
const u8 *str = member->name.str;
size_t len = member->name.len;
parser_error(parser, object_tok, false, "Found multiple times the object member '%.*s'", len, str);
}
}
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}
return &object->base;
}
static Ast *
cond(Parser *parser)
{
AST_CREATE(AstConditional, conditional, parser->arena, AST_CONDITIONAL);
eat(parser, TK_IF);
conditional->condition = expression(parser);
eat(parser, TK_THEN);
conditional->consequent = expression(parser);
if (try_eat(parser, TK_ELSE)) {
conditional->alternative = expression(parser);
} else {
conditional->alternative = create_null(parser);
}
return &conditional->base;
}
static Ast *
loop(Parser *parser)
{
AST_CREATE(AstLoop, loop, parser->arena, AST_LOOP);
eat(parser, TK_WHILE);
loop->condition = expression(parser);
eat(parser, TK_DO);
loop->body = expression(parser);
return &loop->base;
}
static Ast *
print(Parser *parser)
{
AST_CREATE(AstPrint, print, parser->arena, AST_PRINT);
eat(parser, TK_PRINT);
eat(parser, TK_LPAREN);
eat(parser, TK_STRING);
Token fmt_tok = prev_tok(parser);
print->format = fmt_tok.str;
size_t formats = 0;
for (size_t i = 0; i < print->format.len; i++) {
switch (print->format.str[i]) {
case '\\': i++; continue;
case '~': formats += 1;
}
}
if (try_eat(parser, TK_COMMA)) {
expression_list(parser, &print->arguments, &print->argument_cnt, TK_COMMA, TK_RPAREN);
} else {
eat(parser, TK_RPAREN);
}
if (formats != print->argument_cnt) {
parser_error(parser, fmt_tok, false, "Invalid number of print arguments: %zu expected, got %zu", formats, print->argument_cnt);
}
return &print->base;
}
static Ast *
paren(Parser *parser)
{
Ast *ast;
eat(parser, TK_LPAREN);
ast = expression(parser);
eat(parser, TK_RPAREN);
return ast;
}
static Ast *
function(Parser *parser)
{
AST_CREATE(AstFunction, function, parser->arena, AST_FUNCTION);
Ast *ast = &function->base;
eat(parser, TK_FUNCTION);
if (tok_is_identifier(peek(parser))) {
AST_CREATE(AstDefinition, definition, parser->arena, AST_DEFINITION);
eat_identifier(parser, &definition->name);
definition->value = &function->base;
ast = &definition->base;
}
eat(parser, TK_LPAREN);
identifier_list(parser, &function->parameters, &function->parameter_cnt, TK_COMMA, TK_RPAREN);
eat(parser, TK_RARROW);
function->body = expression(parser);
return ast;
}
static Ast *
stop(Parser *parser, Ast *left, int rbp)
{
(void) parser;
(void) left;
(void) rbp;
UNREACHABLE();
}
static Ast *
lefterr(Parser *parser, Ast *left, int rbp)
{
(void) left;
(void) rbp;
TokenKind tok = peek(parser);
parser_error(parser, parser->lookahead, true, "Invalid expression continuing/ending token %s", tok_repr[tok]);
// Set the current token to something with low binding power to not get
// into infinite loop of `lefterr`s on the same token.
parser->lookahead.kind = TK_EOF;
return create_null(parser);
}
static Ast *
binop(Parser *parser, Ast *left, int rbp)
{
AST_CREATE(AstMethodCall, method_call, parser->arena, AST_METHOD_CALL);
method_call->object = left;
Token token = discard(parser);
method_call->name = token.str;
method_call->arguments = arena_alloc(parser->arena, sizeof(*method_call->arguments));
method_call->arguments[0] = expression_bp(parser, rbp);
//method_call->arguments = expression_bp(parser, rbp);
method_call->argument_cnt = 1;
return &method_call->base;
}
static Ast *
call(Parser *parser, Ast *left, int rbp)
{
(void) rbp;
eat(parser, TK_LPAREN);
switch (left->kind) {
case AST_FIELD_ACCESS: {
AstFieldAccess *field_access = (AstFieldAccess *) left;
AST_CREATE(AstMethodCall, method_call, parser->arena, AST_METHOD_CALL);
left->kind = AST_METHOD_CALL;
method_call->object = field_access->object;
method_call->name = field_access->field;
expression_list(parser, &method_call->arguments, &method_call->argument_cnt, TK_COMMA, TK_RPAREN);
return &method_call->base;
}
default: {
AST_CREATE(AstFunctionCall, function_call, parser->arena, AST_FUNCTION_CALL);
function_call->function = left;
expression_list(parser, &function_call->arguments, &function_call->argument_cnt, TK_COMMA, TK_RPAREN);
return &function_call->base;
}
}
}
static Ast *
indexing(Parser *parser, Ast *left, int rbp)
{
// rbp not used - delimited by TK_RBRACKET, not by precedence
(void) rbp;
AST_CREATE(AstIndexAccess, index_access, parser->arena, AST_INDEX_ACCESS);
eat(parser, TK_LBRACKET);
index_access->object = left;
index_access->index = expression(parser);
eat(parser, TK_RBRACKET);
return &index_access->base;
}
static Ast *
field(Parser *parser, Ast *left, int rbp)
{
(void) rbp;
AST_CREATE(AstFieldAccess, field_access, parser->arena, AST_FIELD_ACCESS);
eat(parser, TK_DOT);
field_access->object = left;
eat_identifier(parser, &field_access->field);
return &field_access->base;
}
static Ast *
assign(Parser *parser, Ast *left, int rbp)
{
eat(parser, TK_LARROW);
switch (left->kind) {
case AST_VARIABLE_ACCESS: {
AstVariableAccess *variable_access = (AstVariableAccess *) left;
AST_CREATE(AstVariableAssignment, variable_assignment, parser->arena, AST_VARIABLE_ASSIGNMENT);
variable_assignment->name = variable_access->name;
variable_assignment->value = expression_bp(parser, rbp);
return &variable_assignment->base;
}
case AST_FIELD_ACCESS: {
AstFieldAccess *field_access = (AstFieldAccess *) left;
AST_CREATE(AstFieldAssignment, field_assignment, parser->arena, AST_FIELD_ASSIGNMENT);
field_assignment->object = field_access->object;
field_assignment->field = field_access->field;
field_assignment->value = expression_bp(parser, rbp);
return &field_assignment->base;
}
case AST_INDEX_ACCESS: {
AstIndexAccess *index_access = (AstIndexAccess *) left;
AST_CREATE(AstIndexAssignment, index_assignment, parser->arena, AST_INDEX_ASSIGNMENT);
index_assignment->object = index_access->object;
index_assignment->index = index_access->index;
index_assignment->value = expression_bp(parser, rbp);
return &index_assignment->base;
}
default:
parser_error(parser, parser->prev, false, "Invalid assignment left hand side, expected variable, index or field access");
return left;
}
}
static Ast *
eqerr(Parser *parser, Ast *left, int rbp)
{
parser_error(parser, parser->lookahead, false, "Unexpected %s, did you mean to use %s for assignment?", tok_repr[TK_EQUAL], tok_repr[TK_LARROW]);
parser->lookahead.kind = TK_LARROW;
return assign(parser, left, rbp);
}
typedef struct {
Ast *(*nud)(Parser *);
} NullInfo;
#define TOK_NULL(tok, str, nud, led, lbp, rbp) { nud },
TOKENS(TOK_NULL, TOK_NULL, TOK_NULL)
#undef TOK_STR
};
static bool
at_synchronization_point(Parser *parser)
{
if (parser->prev.kind == TK_EOF) {
// nothing to synchronize
return true;
}
if (parser->prev.kind == TK_SEMICOLON && null_info[parser->lookahead.kind].nud != nullerr) {
// an expression separator and a token that starts an expression
return true;
}
return false;
}
typedef struct {
Ast *(*led)(Parser *, Ast *left, int rbp);
int lbp;
int rbp;
} LeftInfo;
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#define TOK_LEFT(tok, str, nud, led, prec, assoc) { led, PREC_##prec, PREC_##prec + (ASSOC_##assoc == ASSOC_LEFT) },
TOKENS(TOK_LEFT, TOK_LEFT, TOK_LEFT)
#undef TOK_STR
};
static Ast *
expression_bp(Parser *parser, int bp)
{
NullInfo ni = null_info[peek(parser)];
Ast *left = ni.nud(parser);
for (;;) {
LeftInfo li = left_info[peek(parser)];
if (li.lbp < bp) {
break;
}
left = li.led(parser, left, li.rbp);
}
return left;
}
static Ast *
top(Parser *parser)
{
AST_CREATE(AstTop, top, parser->arena, AST_TOP);
for (;;) {
expression_list(parser, &top->expressions, &top->expression_cnt, TK_SEMICOLON, TK_EOF);
if (!parser->panic_mode) {
break;
}
do {
discard(parser);
} while (!at_synchronization_point(parser));
parser->panic_mode = false;
}
// empty program => null
if (top->expression_cnt == 0) {
top->base.kind = AST_NULL;
}
return &top->base;
}
void
parser_error_cb(void *user_data, const u8 *err_pos, const char *msg, va_list ap)
{
Str *src = user_data;
const u8 *line_start = src->str;
size_t line = 0;
const u8 *pos = src->str;
for (; pos < err_pos; pos++) {
if (*pos == '\n') {
line_start = pos + 1;
line++;
}
}
size_t col = pos - line_start;
const u8 *source_end = src->str + src->len;
const u8 *line_end = pos;
for (; line_end < source_end && *line_end != '\n'; line_end++) {}
fprintf(stderr, "[%zu:%zu]: parser error: ", line + 1, col + 1);
vfprintf(stderr, msg, ap);
fprintf(stderr, "\n");
fprintf(stderr, " %.*s\n", (int) (line_end - line_start), line_start);
fprintf(stderr, " %*s\n", (int) (pos - line_start + 1), "^");
}
Ast *
parse(Arena *arena, GArena *scratch, Str source, void (*error_callback)(void *user_data, const u8 *err_pos, const char *msg, va_list ap), void *user_data)
{
Parser parser = {
.arena = arena,
.scratch = scratch,
.user_data = user_data,
.error_callback = error_callback,
.lexer = lex_create(source),
.had_error = false,
.panic_mode = false,
};
discard(&parser);
Ast *ast = top(&parser);
if (parser.had_error) {
return NULL;
}
return ast;
}
Ast *
parse_src(Arena *arena, Str source)
{
GArena scratch;
garena_init(&scratch);
Ast *ast = parse(arena, &scratch, source, parser_error_cb, &source);
garena_destroy(&scratch);
return ast;
}