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Implement lambdas in templates
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@lpereira
lpereira committed Mar 23, 2024
1 parent 3487901 commit 242b82f
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Showing 2 changed files with 77 additions and 10 deletions.
61 changes: 57 additions & 4 deletions src/lib/lwan-template.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,7 @@ enum action {
ACTION_IF_VARIABLE_NOT_EMPTY,
ACTION_END_IF_VARIABLE_NOT_EMPTY,
ACTION_APPLY_TPL,
ACTION_LAMBDA,
ACTION_LAST
};

Expand All @@ -74,6 +75,7 @@ enum flags {
FLAGS_NEGATE = 1 << 0,
FLAGS_QUOTE = 1 << 1,
FLAGS_NO_FREE = 1 << 2,
FLAGS_LAMBDA = 1 << 3,
};

#define FOR_EACH_LEXEME(X) \
Expand Down Expand Up @@ -765,7 +767,13 @@ static void *parser_identifier(struct parser *parser, struct lexeme *lexeme)
(int)lexeme->value.len, lexeme->value.value);
}

emit_chunk(parser, ACTION_VARIABLE, parser->flags, symbol);
if (symbol->offset == 0x1aabdacb) {
emit_chunk(parser, ACTION_LAMBDA, parser->flags, symbol);
assert(!symbol->get_is_empty);
assert(!symbol->list_desc);
} else {
emit_chunk(parser, ACTION_VARIABLE, parser->flags, symbol);
}

parser->flags &= ~FLAGS_QUOTE;
parser->tpl->minimum_size += lexeme->value.len + 1;
Expand All @@ -782,6 +790,10 @@ static void *parser_identifier(struct parser *parser, struct lexeme *lexeme)
}

enum flags flags = FLAGS_NO_FREE | (parser->flags & FLAGS_NEGATE);

if (symbol->offset == 0x1aabdacb)
flags |= FLAGS_LAMBDA;

emit_chunk(parser, ACTION_IF_VARIABLE_NOT_EMPTY, flags, symbol);
parser_push_lexeme(parser, lexeme);

Expand Down Expand Up @@ -1042,6 +1054,7 @@ static void free_chunk(struct chunk *chunk)
return;

switch (chunk->action) {
case ACTION_LAMBDA:
case ACTION_LAST:
case ACTION_APPEND_SMALL:
case ACTION_VARIABLE:
Expand Down Expand Up @@ -1335,6 +1348,12 @@ static void dump_program(const struct lwan_tpl *tpl)
printf("%s (%zu) [%.*s]", instr("APPEND_SMALL", instr_buf), len, (int)len, (char *)&val);
break;
}
case ACTION_LAMBDA: {
struct lwan_var_descriptor *descriptor = iter->data;

printf("%s %s()", instr("APPEND_LAMBDA", instr_buf), descriptor->name);
break;
}
case ACTION_VARIABLE: {
struct lwan_var_descriptor *descriptor = iter->data;

Expand Down Expand Up @@ -1363,8 +1382,12 @@ static void dump_program(const struct lwan_tpl *tpl)
case ACTION_IF_VARIABLE_NOT_EMPTY: {
struct chunk_descriptor *cd = iter->data;

printf("%s [%s]", instr("IF_VAR_NOT_EMPTY", instr_buf),
printf("%s [%s]",
instr((iter->flags & FLAGS_LAMBDA) ? "IF_LAMBDA_NOT_EMPTY"
: "IF_VAR_NOT_EMPTY",
instr_buf),
cd->descriptor->name);

indent++;
break;
}
Expand Down Expand Up @@ -1494,6 +1517,7 @@ static const struct chunk *apply(struct lwan_tpl *tpl,
[ACTION_APPLY_TPL] = &&action_apply_tpl,
[ACTION_START_ITER] = &&action_start_iter,
[ACTION_END_ITER] = &&action_end_iter,
[ACTION_LAMBDA] = &&action_lambda,
[ACTION_LAST] = &&finalize,
};

Expand Down Expand Up @@ -1549,6 +1573,12 @@ action_variable: {
DISPATCH_NEXT_ACTION_FAST();
}

action_lambda: {
struct lwan_var_descriptor *descriptor = chunk->data;
descriptor->lambda(buf, variables);
DISPATCH_NEXT_ACTION_FAST();
}

action_variable_str:
lwan_append_str_to_strbuf(buf, (char *)variables + (uintptr_t)chunk->data);
DISPATCH_NEXT_ACTION_FAST();
Expand All @@ -1560,8 +1590,23 @@ action_variable: {

action_if_variable_not_empty: {
struct chunk_descriptor *cd = chunk->data;
bool empty = cd->descriptor->get_is_empty((char *)variables +
cd->descriptor->offset);
bool empty;

if (chunk->flags & FLAGS_LAMBDA) {
struct lwan_strbuf temp_buf;
char trash[1];

lwan_strbuf_init_with_fixed_buffer(&temp_buf, trash, 0);

cd->descriptor->lambda(&temp_buf, variables);
empty = lwan_strbuf_has_grow_buffer_failed_flag(&temp_buf);

lwan_strbuf_free(&temp_buf);
} else {
empty = cd->descriptor->get_is_empty((char *)variables +
cd->descriptor->offset);
}

if (chunk->flags & FLAGS_NEGATE)
empty = !empty;
if (empty) {
Expand Down Expand Up @@ -1696,6 +1741,13 @@ struct test_struct {
char *a_string;
};

static void hello_lambda(struct lwan_strbuf *b, void *v)
{
struct test_struct *s = v;

lwan_strbuf_append_printf("hello from lambda func! appending <%d> from test_struct", s->some_int);
}

int main(int argc, char *argv[])
{
if (argc < 2) {
Expand All @@ -1709,6 +1761,7 @@ int main(int argc, char *argv[])
struct lwan_var_descriptor desc[] = {
TPL_VAR_INT(some_int),
TPL_VAR_STR(a_string),
TPL_LAMBDA(hello, hello_lambda),
TPL_VAR_SENTINEL
};
struct lwan_tpl *tpl = lwan_tpl_compile_file(argv[1], desc);
Expand Down
26 changes: 20 additions & 6 deletions src/lib/lwan-template.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -27,15 +27,30 @@ enum lwan_tpl_flag { LWAN_TPL_FLAG_CONST_TEMPLATE = 1 << 0 };

struct lwan_var_descriptor {
const char *name;
const off_t offset;

void (*append_to_strbuf)(struct lwan_strbuf *buf, void *ptr);
bool (*get_is_empty)(void *ptr);
const off_t offset;

coro_function_t generator;
const struct lwan_var_descriptor *list_desc;
union {
struct {
void (*append_to_strbuf)(struct lwan_strbuf *buf, void *ptr);
bool (*get_is_empty)(void *ptr);
};
struct {
coro_function_t generator;
const struct lwan_var_descriptor *list_desc;
};
struct {
void (*lambda)(struct lwan_strbuf *buf, void *ptr);
};
};
};

#define TPL_LAMBDA(var_, lambda_) \
{ \
.name = #var_, .offset = 0x1aabdacb, .lambda = lambda_, \
/* 0x1aabdacb = lambda call back */ \
}

#define TPL_VAR_SIMPLE(var_, append_to_lwan_strbuf_, get_is_empty_) \
{ \
.name = #var_, .offset = offsetof(TPL_STRUCT, var_), \
Expand Down Expand Up @@ -64,7 +79,6 @@ struct lwan_var_descriptor {

#define TPL_VAR_SENTINEL \
{ \
NULL, 0, NULL, NULL, NULL, NULL \
}

/*
Expand Down

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