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#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <stdalign.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include "alloc.h"
#include "common.h"
#include "errors.h"
#include "parser.h"
/* #define AST_DFLT_CAP (2048) */
#define AST_DFLT_CAP (8)
#define SIZE_WDTH (sizeof(size_t) * CHAR_BIT)
typedef idx_t_ parsefn(struct ast *, struct lexemes);
static parsefn parseblk,
parsedecl,
parseexpr,
parseproto,
parsestmt,
parsetype;
static struct ast mkast(void);
static idx_t_ astalloc(struct ast *) __attribute__((nonnull));
static void astresz(struct ast *) __attribute__((nonnull));
static size_t toksidx;
struct ast
parsetoks(struct lexemes toks)
{
struct ast ast = mkast();
for (;;) {
parsedecl(&ast, toks);
if (toks.kinds[toksidx] == LEXEOF)
break;
}
return ast;
}
idx_t_
parseblk(struct ast *ast, struct lexemes toks)
{
idx_t_ i = astalloc(ast);
ast->lexemes[i] = toksidx;
ast->kinds[i] = ASTBLK;
ast->kids[i].lhs = ast->kids[i].rhs = AST_EMPTY;
if (toks.kinds[toksidx++] != LEXLBRACE)
err("parser: Expected left brace");
while (toks.kinds[toksidx] != LEXRBRACE) {
ast->kids[i].rhs = parsestmt(ast, toks);
if (ast->kids[i].lhs == AST_EMPTY)
ast->kids[i].lhs = ast->kids[i].rhs;
}
toksidx++; /* Eat rbrace */
return i;
}
idx_t_
parsedecl(struct ast *ast, struct lexemes toks)
{
idx_t_ i = astalloc(ast);
ast->lexemes[i] = toksidx;
if (toks.kinds[toksidx++] != LEXIDENT)
err("parser: Expected identifier");
if (toks.kinds[toksidx++] != LEXCOLON)
err("parser: Expected colon");
ast->kids[i].lhs = toks.kinds[toksidx] == LEXIDENT
? parsetype(ast, toks)
: AST_EMPTY;
switch (toks.kinds[toksidx++]) {
case LEXSEMI:
if (ast->kids[i].lhs == AST_EMPTY)
err("parser: No type provided in non-assigning declaration");
ast->kinds[i] = ASTDECL;
ast->kids[i].rhs = AST_EMPTY;
return i;
case LEXCOLON:
ast->kinds[i] = ASTCDECL;
break;
case LEXEQ:
ast->kinds[i] = ASTDECL;
break;
default:
err("parser: Expected semicolon or equals");
}
ast->kids[i].rhs = parseexpr(ast, toks);
if (toks.kinds[toksidx++] != LEXSEMI)
err("parser: Expected semicolon");
return i;
}
idx_t_
parseexpr(struct ast *ast, struct lexemes toks)
{
idx_t_ i = astalloc(ast);
ast->lexemes[i] = toksidx;
switch (toks.kinds[toksidx]) {
case LEXNUM:
toksidx++;
ast->kinds[i] = ASTNUMLIT;
break;
case LEXLPAR:
ast->kinds[i] = ASTFN;
ast->kids[i].lhs = parseproto(ast, toks);
ast->kids[i].rhs = parseblk(ast, toks);
break;
default:
err("parser: Expected expression");
}
return i;
}
idx_t_
parseproto(struct ast *ast, struct lexemes toks)
{
idx_t_ i = astalloc(ast);
ast->lexemes[i] = toksidx;
ast->kinds[i] = ASTFNPROTO;
ast->kids[i].lhs = AST_EMPTY;
if (toks.kinds[toksidx++] != LEXLPAR)
err("parser: Expected left parenthesis");
if (toks.kinds[toksidx++] != LEXRPAR)
err("parser: Expected right parenthesis");
ast->kids[i].rhs = toks.kinds[toksidx] == LEXIDENT
? parsetype(ast, toks)
: AST_EMPTY;
return i;
}
idx_t_
parsestmt(struct ast *ast, struct lexemes toks)
{
idx_t_ i;
if (toks.kinds[toksidx] != LEXIDENT)
err("parser: Expected identifier");
struct strview sv = toks.strs[toksidx];
if (strncmp("return", sv.p, sv.len) == 0) {
i = astalloc(ast);
ast->lexemes[i] = toksidx++;
ast->kinds[i] = ASTRET;
if (toks.kinds[toksidx] != LEXSEMI)
ast->kids[i].rhs = parseexpr(ast, toks);
else
ast->kids[i].rhs = AST_EMPTY;
if (toks.kinds[toksidx++] != LEXSEMI)
err("parser: Expected semicolon");
} else if (toks.kinds[toksidx + 1] == LEXCOLON)
i = parsedecl(ast, toks);
else
i = parseexpr(ast, toks);
return i;
}
idx_t_
parsetype(struct ast *ast, struct lexemes toks)
{
idx_t_ i = astalloc(ast);
ast->kinds[i] = ASTTYPE;
ast->lexemes[i] = toksidx;
if (toks.kinds[toksidx++] != LEXIDENT)
err("parser: Expected type");
return i;
}
struct ast
mkast(void)
{
struct ast soa;
static_assert(AST_DFLT_CAP * sizeof(*soa.kinds) % alignof(*soa.lexemes)
== 0,
"Additional padding is required to properly align LEXEMES");
static_assert(AST_DFLT_CAP * (sizeof(*soa.kinds) + sizeof(*soa.lexemes))
% alignof(*soa.kids)
== 0,
"Additional padding is required to properly align KIDS");
soa.len = 0;
soa.cap = AST_DFLT_CAP;
soa.kinds = bufalloc(NULL, soa.cap, AST_SOA_BLKSZ);
soa.lexemes = (void *)((char *)soa.kinds + soa.cap * sizeof(*soa.kinds));
soa.kids = (void *)((char *)soa.lexemes + soa.cap * sizeof(*soa.lexemes));
return soa;
}
void
astresz(struct ast *soa)
{
size_t ncap, pad1, pad2, newsz;
ptrdiff_t lexemes_off, kids_off;
lexemes_off = (char *)soa->lexemes - (char *)soa->kinds;
kids_off = (char *)soa->kids - (char *)soa->kinds;
/* The capacity is always going to be a power of 2, so checking for overflow
becomes pretty trivial */
if ((soa->cap >> (SIZE_WDTH - 1)) != 0) {
errno = EOVERFLOW;
err("%s:", __func__);
}
ncap = soa->cap << 1;
/* Ensure that soa->lexemes is properly aligned */
pad1 = alignof(*soa->lexemes)
- ncap * sizeof(*soa->kinds) % alignof(*soa->lexemes);
if (pad1 == alignof(*soa->lexemes))
pad1 = 0;
/* Ensure that soa->kids is properly aligned */
pad2 = alignof(*soa->kids)
- (ncap * (sizeof(*soa->kinds) + sizeof(*soa->lexemes)) + pad1)
% alignof(*soa->kids);
if (pad2 != alignof(*soa->kids))
pad2 = 0;
newsz = ncap * AST_SOA_BLKSZ + pad1 + pad2;
soa->kinds = bufalloc(soa->kinds, newsz, 1);
soa->lexemes = (void *)((char *)soa->kinds + ncap * sizeof(*soa->kinds)
+ pad1);
soa->kids = (void *)((char *)soa->lexemes + ncap * sizeof(*soa->lexemes)
+ pad2);
memmove(soa->kids, (char *)soa->kinds + kids_off,
soa->len * sizeof(*soa->kids));
memmove(soa->lexemes, (char *)soa->kinds + lexemes_off,
soa->len * sizeof(*soa->lexemes));
soa->cap = ncap;
}
idx_t_
astalloc(struct ast *soa)
{
if (soa->len == soa->cap)
astresz(soa);
return soa->len++;
}
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