commit 258111393367df7d8b68fa16e19ced601f96b6b2
parent b41f42ca3178ac004280708d3e40b5265c9b8920
Author: Drew DeVault <sir@cmpwn.com>
Date: Tue, 22 Dec 2020 15:57:13 -0500
parser: refactor parser to return expressions
Diffstat:
4 files changed, 59 insertions(+), 91 deletions(-)
diff --git a/include/ast.h b/include/ast.h
@@ -138,7 +138,7 @@ struct ast_global_decl {
char *symbol;
struct identifier ident;
struct ast_type type;
- struct ast_expression init;
+ struct ast_expression *init;
struct ast_global_decl *next;
};
@@ -152,7 +152,7 @@ struct ast_function_decl {
char *symbol;
struct identifier ident;
struct ast_function_type prototype;
- struct ast_expression body;
+ struct ast_expression *body;
unsigned int flags; // enum func_decl_flags (check.h)
};
diff --git a/src/check.c b/src/check.c
@@ -286,7 +286,7 @@ check_function(struct context *ctx,
}
struct expression *body = calloc(1, sizeof(struct expression));
- check_expression(ctx, &afndecl->body, body);
+ check_expression(ctx, afndecl->body, body);
decl->func.body = body;
// TODO: Check assignability of expression result to function type
diff --git a/src/parse.c b/src/parse.c
@@ -371,10 +371,8 @@ parse_type(struct parser *par, struct ast_type *type)
type_storage_unparse(type->storage));
}
-static void parse_complex_expression(struct parser *par,
- struct ast_expression *exp);
-static void parse_simple_expression(struct parser *par,
- struct ast_expression *exp);
+static struct ast_expression *parse_complex_expression(struct parser *par);
+static struct ast_expression *parse_simple_expression(struct parser *par);
/*
static void
@@ -387,10 +385,11 @@ parse_access(struct parser *par, struct ast_expression *exp)
}
*/
-static void
-parse_binding_list(struct parser *par, struct ast_expression *exp)
+static struct ast_expression *
+parse_binding_list(struct parser *par)
{
trenter(TR_PARSE, "binding-list");
+ struct ast_expression *exp = calloc(1, sizeof(struct ast_expression));
exp->type = EXPR_BINDING;
unsigned int flags = 0;
@@ -423,10 +422,10 @@ parse_binding_list(struct parser *par, struct ast_expression *exp)
parse_type(par, binding->type);
binding->type->flags |= flags;
want(par, T_EQUAL, &tok);
- parse_complex_expression(par, binding->initializer);
+ binding->initializer = parse_complex_expression(par);
break;
case T_EQUAL:
- parse_simple_expression(par, binding->initializer);
+ binding->initializer = parse_simple_expression(par);
break;
default:
synassert(false, &tok, T_COLON, T_COMMA, T_EOF);
@@ -446,17 +445,21 @@ parse_binding_list(struct parser *par, struct ast_expression *exp)
}
trleave(TR_PARSE, NULL);
+ return exp;
}
-static void
-parse_constant(struct parser *par, struct ast_expression *exp)
+static struct ast_expression *
+parse_constant(struct parser *par)
{
trenter(TR_PARSE, "constant");
struct token tok = {0};
want(par, T_LITERAL, &tok);
+
+ struct ast_expression *exp = calloc(1, sizeof(struct ast_expression));
exp->type = EXPR_CONSTANT;
exp->constant.storage = tok.storage;
+
switch (tok.storage) {
case TYPE_STORAGE_CHAR:
case TYPE_STORAGE_U8:
@@ -486,14 +489,13 @@ parse_constant(struct parser *par, struct ast_expression *exp)
assert(0); // TODO
}
trleave(TR_PARSE, "%s", token_str(&tok));
-
- trleave(TR_PARSE, NULL);
+ return exp;
}
-static void
-parse_cast_expression(struct parser *par, struct ast_expression *exp)
+static struct ast_expression *
+parse_cast_expression(struct parser *par)
{
- parse_constant(par, exp); // TODO
+ return parse_constant(par); // TODO
}
static int
@@ -582,14 +584,11 @@ binop_for_token(enum lexical_token tok)
assert(0); // Unreachable
}
-static void
-parse_bin_expression2(struct parser *par, struct ast_expression *exp,
- struct ast_expression *lvalue, int i)
+static struct ast_expression *
+parse_bin_expression(struct parser *par, struct ast_expression *lvalue, int i)
{
if (!lvalue) {
- // XXX: This probably creates a memory leak
- lvalue = calloc(1, sizeof(struct ast_expression));
- parse_cast_expression(par, lvalue);
+ lvalue = parse_cast_expression(par);
}
struct token tok;
@@ -597,51 +596,36 @@ parse_bin_expression2(struct parser *par, struct ast_expression *exp,
int j;
while ((j = precedence(tok.token)) >= i) {
- exp->type = EXPR_BINARITHM;
- exp->binarithm.op = binop_for_token(tok.token);
-
- struct ast_expression *rvalue =
- calloc(1, sizeof(struct ast_expression));
- parse_cast_expression(par, rvalue);
+ lvalue->type = EXPR_BINARITHM;
+ lvalue->binarithm.op = binop_for_token(tok.token);
+ struct ast_expression *rvalue = parse_cast_expression(par);
lex(par->lex, &tok);
int k;
while ((k = precedence(tok.token)) > j) {
- struct ast_expression *rvalue2 =
- calloc(1, sizeof(struct ast_expression));
unlex(par->lex, &tok);
- parse_bin_expression2(par, rvalue2, rvalue, k);
- rvalue = rvalue2;
+ rvalue = parse_bin_expression(par, rvalue, k);
lex(par->lex, &tok);
}
- exp->binarithm.lvalue = lvalue;
- exp->binarithm.rvalue = rvalue;
- lvalue = exp;
+ lvalue->binarithm.lvalue = lvalue;
+ lvalue->binarithm.rvalue = rvalue;
}
unlex(par->lex, &tok);
- *exp = *lvalue;
+ return lvalue;
}
-static void
-parse_bin_expression(struct parser *par, struct ast_expression *exp)
+static struct ast_expression *
+parse_simple_expression(struct parser *par)
{
- parse_bin_expression2(par, exp, NULL, 0);
+ return parse_bin_expression(par, NULL, 0);
}
-static void
-parse_simple_expression(struct parser *par, struct ast_expression *exp)
+static struct ast_expression *
+parse_complex_expression(struct parser *par)
{
- parse_bin_expression(par, exp);
-}
-
-static void
-parse_complex_expression(struct parser *par, struct ast_expression *exp)
-{
- trenter(TR_PARSE, "complex-expression");
-
struct token tok;
switch (lex(par->lex, &tok)) {
case T_IF:
@@ -651,42 +635,35 @@ parse_complex_expression(struct parser *par, struct ast_expression *exp)
assert(0); // TODO
default:
unlex(par->lex, &tok);
- parse_simple_expression(par, exp);
- break;
+ return parse_simple_expression(par);
}
-
- trleave(TR_PARSE, NULL);
}
-static void
-parse_scope_expression(struct parser *par, struct ast_expression *exp)
+static struct ast_expression *
+parse_scope_expression(struct parser *par)
{
- trenter(TR_PARSE, "scope-expression");
-
struct token tok;
switch (lex(par->lex, &tok)) {
case T_LET:
case T_CONST:
unlex(par->lex, &tok);
- parse_binding_list(par, exp);
- break;
+ return parse_binding_list(par);
case T_STATIC:
assert(0); // Binding list or assert
default:
unlex(par->lex, &tok);
- parse_complex_expression(par, exp);
- break;
+ return parse_complex_expression(par);
// TODO: allocations, assignments
}
-
- trleave(TR_PARSE, NULL);
}
-static void
-parse_control_statement(struct parser *par, struct ast_expression *exp)
+static struct ast_expression *
+parse_control_statement(struct parser *par)
{
trenter(TR_PARSE, "control-expression");
+ struct ast_expression *exp = calloc(1, sizeof(struct ast_expression));
+
struct token tok;
switch (lex(par->lex, &tok)) {
case T_BREAK:
@@ -703,9 +680,7 @@ parse_control_statement(struct parser *par, struct ast_expression *exp)
break;
default:
unlex(par->lex, &tok);
- exp->_return.value =
- calloc(1, sizeof(struct ast_expression));
- parse_complex_expression(par, exp->_return.value);
+ exp->_return.value = parse_complex_expression(par);
break;
}
break;
@@ -714,36 +689,34 @@ parse_control_statement(struct parser *par, struct ast_expression *exp)
}
trleave(TR_PARSE, NULL);
+ return exp;
}
-static void
-parse_expression_list(struct parser *par, struct ast_expression *exp)
+static struct ast_expression *
+parse_expression_list(struct parser *par)
{
trenter(TR_PARSE, "expression-list");
want(par, T_LBRACE, NULL);
- exp->type = EXPR_LIST;
+ struct ast_expression *exp = calloc(1, sizeof(struct ast_expression));
struct ast_expression_list *cur = &exp->list;
struct ast_expression_list **next = &cur->next;
+ exp->type = EXPR_LIST;
bool more = true;
while (more) {
- struct ast_expression *curexp =
- calloc(1, sizeof(struct ast_expression));
- cur->expr = curexp;
-
struct token tok = {0};
switch (lex(par->lex, &tok)) {
case T_BREAK:
case T_CONTINUE:
case T_RETURN:
unlex(par->lex, &tok);
- parse_control_statement(par, curexp);
+ cur->expr = parse_control_statement(par);
more = false;
break;
default:
unlex(par->lex, &tok);
- parse_scope_expression(par, curexp);
+ cur->expr = parse_scope_expression(par);
break;
}
@@ -765,24 +738,21 @@ parse_expression_list(struct parser *par, struct ast_expression *exp)
}
trleave(TR_PARSE, NULL);
+ return exp;
}
-static void
-parse_compound_expression(struct parser *par, struct ast_expression *exp)
+static struct ast_expression *
+parse_compound_expression(struct parser *par)
{
- trenter(TR_PARSE, "compound-expression");
struct token tok = {0};
switch (lex(par->lex, &tok)) {
case T_LBRACE:
unlex(par->lex, &tok);
- parse_expression_list(par, exp);
- break;
+ return parse_expression_list(par);
default:
unlex(par->lex, &tok);
- parse_simple_expression(par, exp);
- break;
+ return parse_simple_expression(par);
}
- trleave(TR_PARSE, NULL);
}
static char *
@@ -831,7 +801,7 @@ parse_global_decl(struct parser *par, enum lexical_token mode,
i->type.flags |= TYPE_CONST;
}
want(par, T_EQUAL, NULL);
- parse_simple_expression(par, &i->init);
+ i->init = parse_simple_expression(par);
switch (lex(par->lex, &tok)) {
case T_COMMA:
lex(par->lex, &tok);
@@ -933,7 +903,7 @@ parse_fn_decl(struct parser *par, struct ast_function_decl *decl)
parse_identifier(par, &decl->ident);
parse_prototype(par, &decl->prototype);
want(par, T_EQUAL, NULL);
- parse_compound_expression(par, &decl->body);
+ decl->body = parse_compound_expression(par);
char symbol[1024], buf[1024];
if (decl->symbol) {
diff --git a/todo.txt b/todo.txt
@@ -2,8 +2,6 @@ highest priorities, unordered except where there are obvious dependencies:
- variable assignment
- simple binary and unary arithmetic
-- refactor parser (and AST) to have each parse_* function return a heap
- allocated expression, rather than accept a pointer to one
- aggregate types
- in parameters
- in variables
