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Handle 'null' with defaults #19

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1a2c047
jimp: Handle 'null' with defaults
Jun 28, 2025
6447633
jimp: Add example for defaults
Jun 28, 2025
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10 changes: 5 additions & 5 deletions examples/03_parsing_database.c
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Original file line number Diff line number Diff line change
Expand Up @@ -24,13 +24,13 @@ bool parse_person(Jimp *jimp, Person *p)
if (!jimp_object_begin(jimp)) return false;
while (jimp_object_member(jimp)) {
if (strcmp(jimp->member, "name") == 0) {
if (!jimp_string(jimp, &p->name)) return false;
if (!jimp_string(jimp, &p->name, NULL)) return false;
} else if (strcmp(jimp->member, "age") == 0) {
if (!jimp_number(jimp, &p->age)) return false;
if (!jimp_number(jimp, &p->age, 0)) return false;
} else if (strcmp(jimp->member, "location") == 0) {
if (!jimp_string(jimp, &p->location)) return false;
if (!jimp_string(jimp, &p->location, NULL)) return false;
} else if (strcmp(jimp->member, "body_count") == 0) {
if (!jimp_number(jimp, &p->body_count)) return false;
if (!jimp_number(jimp, &p->body_count, 0)) return false;
} else {
jimp_unknown_member(jimp);
return false;
Expand Down Expand Up @@ -93,7 +93,7 @@ int main()
if (!jimp_array_begin(&jimp)) return 1;
while (jimp_array_item(&jimp)) {
double x = 0;
if (!jimp_number(&jimp, &x)) return 1;
if (!jimp_number(&jimp, &x, 0)) return 1;
da_append(&xs, x);
}
if (!jimp_array_end(&jimp)) return 1;
Expand Down
132 changes: 132 additions & 0 deletions examples/04_parsing_defaults.c
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Original file line number Diff line number Diff line change
@@ -0,0 +1,132 @@
#include <stdio.h>
#include <stdbool.h>
#define NOB_IMPLEMENTATION
#define NOB_STRIP_PREFIX
#include "../thirdparty/nob.h"
#define JIMP_IMPLEMENTATION
#include "../jimp.h"

typedef struct {
const char *name;
double age;
const char *location;
double body_count;
} Person;

typedef struct {
Person *items;
size_t count;
size_t capacity;
} People;

bool parse_person(Jimp *jimp, Person *p)
{
if (!jimp_object_begin(jimp)) return false;
while (jimp_object_member(jimp)) {
if (strcmp(jimp->member, "name") == 0) {
if (!jimp_string(jimp, &p->name, strdup("Default Name"))) return false;
} else if (strcmp(jimp->member, "age") == 0) {
if (!jimp_number(jimp, &p->age, 18)) return false;
} else if (strcmp(jimp->member, "location") == 0) {
if (!jimp_string(jimp, &p->location, strdup("UNKNOWN"))) return false;
} else if (strcmp(jimp->member, "body_count") == 0) {
if (!jimp_number(jimp, &p->body_count, 69)) return false;
} else {
jimp_unknown_member(jimp);
return false;
}
}
return jimp_object_end(jimp);
}

bool parse_people(Jimp *jimp, People *ps)
{
if (!jimp_array_begin(jimp)) return false;
while (jimp_array_item(jimp)) {
Person p = {0}; // jimp_object_* uses this value as its default
if (!parse_person(jimp, &p)) return false;
da_append(ps, p);
}
if (!jimp_array_end(jimp)) return false;

return true;
}

void print_person(const Person *p)
{
printf("name = %s\n", p->name);
printf("age = %lf\n", p->age);
printf("location = %s\n", p->location);
printf("body_count = %lf\n", p->body_count);
}

typedef struct {
long *items;
size_t count;
size_t capacity;
} Numbers;

int main()
{
const char *file_path = "database_default.json";
String_Builder sb = {0};
if (!read_entire_file(file_path, &sb)) return 1;
Jimp jimp = {
.file_path = file_path,
.start = sb.items,
.end = sb.items + sb.count,
.point = sb.items,
};

People ps = {0};
Numbers xs = {0};
Numbers xs_null = {0};
if (!jimp_object_begin(&jimp)) return 1;
while (jimp_object_member(&jimp)) {
if (strcmp(jimp.member, "profile") == 0) {
if (!parse_people(&jimp, &ps)) return 1;
} else if (strcmp(jimp.member, "number") == 0) {
if (!jimp_array_begin(&jimp)) return 1;
while (jimp_array_item(&jimp)) {
double x;
if (!jimp_number(&jimp, &x, 0)) return 1;
da_append(&xs, x);
}
if (!jimp_array_end(&jimp)) return 1;
} else if (strcmp(jimp.member, "array_null") == 0) {
// The default for array is an empty array
if (!jimp_array_begin(&jimp)) return 1;
while (jimp_array_item(&jimp)) {
double x;
if (!jimp_number(&jimp, &x, 0)) return 1;
da_append(&xs_null, x);
}
if (!jimp_array_end(&jimp)) return 1;
} else {
jimp_unknown_member(&jimp);
return 1;
}
}
if (!jimp_object_end(&jimp)) return 1;

da_foreach(Person, p, &ps) {
print_person(p);
printf("\n");
}
printf("------------------------------\n");
da_foreach(long, x, &xs) {
printf("%ld ", *x);
}
printf("\n");
printf("------------------------------\n");
if(xs_null.count == 0) {
printf("[]\n");
} else {
da_foreach(long, x, &xs_null) {
printf("%ld ", *x);
}
}
printf("\n");

return 0;
}
5 changes: 4 additions & 1 deletion examples/Makefile
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
CFLAGS=-Wall -Wextra -Wswitch-enum -ggdb

.PHONY: all
all: 01_from_readme 02_binary_tree 03_parsing_database
all: 01_from_readme 02_binary_tree 03_parsing_database 04_parsing_defaults

01_from_readme: 01_from_readme.c ../jim.h
$(CC) $(CFLAGS) -o 01_from_readme 01_from_readme.c
Expand All @@ -11,3 +11,6 @@ all: 01_from_readme 02_binary_tree 03_parsing_database

03_parsing_database: 03_parsing_database.c ../jimp.h ../thirdparty/nob.h
$(CC) $(CFLAGS) -o 03_parsing_database 03_parsing_database.c

04_parsing_defaults: 04_parsing_defaults.c ../jimp.h ../thirdparty/nob.h
$(CC) $(CFLAGS) -o 04_parsing_defaults 04_parsing_defaults.c
26 changes: 26 additions & 0 deletions examples/database_default.json
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Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
{
"number": [69, 420, null, 80085],
"array_null": null,
"profile": [
{
"location": "Wonderland",
"location": "Wonderland",
"body_count": 150,
"name": "Alice Smith",
"age": 34
},
{
"name": null,
"age": 45,
"location": "Atlantis",
"body_count": null
},
{
"name": "Ian Malcolm",
"age": 60,
"location": null,
"body_count": 400
},
null
]
}
107 changes: 74 additions & 33 deletions jimp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -50,12 +50,12 @@ typedef struct {
double number;

const char *member;
bool value_is_null;
} Jimp;

// TODO: how do null-s fit into this entire system?
bool jimp_bool(Jimp *jimp, bool *boolean);
bool jimp_number(Jimp *jimp, double *number);
bool jimp_string(Jimp *jimp, const char **string);
bool jimp_bool(Jimp *jimp, bool *boolean, bool defaultt);
bool jimp_number(Jimp *jimp, double *number, double defaultt);
bool jimp_string(Jimp *jimp, const char **string, const char*defaultt);
bool jimp_object_begin(Jimp *jimp);
bool jimp_object_member(Jimp *jimp);
bool jimp_object_end(Jimp *jimp);
Expand Down Expand Up @@ -200,37 +200,50 @@ void jimp_diagf(Jimp *jimp, const char *fmt, ...)

static const char *jimp__token_kind(Jimp_Token token)
{
switch (token) {
case JIMP_EOF: return "end of input";
case JIMP_INVALID: return "invalid";
case JIMP_OCURLY: return "{";
case JIMP_CCURLY: return "}";
case JIMP_OBRACKET: return "[";
case JIMP_CBRACKET: return "]";
case JIMP_COMMA: return ",";
case JIMP_COLON: return ":";
case JIMP_TRUE: return "true";
case JIMP_FALSE: return "false";
case JIMP_NULL: return "null";
case JIMP_STRING: return "string";
case JIMP_NUMBER: return "number";
}
assert(0 && "unreachable");
return NULL;
switch (token) {
case JIMP_EOF: return "end of input";
case JIMP_INVALID: return "invalid";
case JIMP_OCURLY: return "{";
case JIMP_CCURLY: return "}";
case JIMP_OBRACKET: return "[";
case JIMP_CBRACKET: return "]";
case JIMP_COMMA: return ",";
case JIMP_COLON: return ":";
case JIMP_TRUE: return "true";
case JIMP_FALSE: return "false";
case JIMP_NULL: return "null";
case JIMP_STRING: return "string";
case JIMP_NUMBER: return "number";
}
assert(0 && "unreachable");
return NULL;
}

bool jimp_array_begin(Jimp *jimp)
{
return jimp__get_and_expect_token(jimp, JIMP_OBRACKET);
if (!jimp__get_token(jimp)) return false;
if(jimp->token == JIMP_NULL) {
jimp->value_is_null = true;
return true;
} else if(jimp->token != JIMP_OBRACKET) {
jimp_diagf(jimp, "ERROR: expected `%s` or `%s`, but got `%s`\n", jimp__token_kind(JIMP_OBRACKET), jimp__token_kind(JIMP_NULL), jimp__token_kind(jimp->token));
return false;
}
return true;
}

bool jimp_array_end(Jimp *jimp)
{
if(jimp->value_is_null) {
jimp->value_is_null = false;
return true;
}
return jimp__get_and_expect_token(jimp, JIMP_CBRACKET);
}

bool jimp_array_item(Jimp *jimp)
{
if(jimp->value_is_null) return false;
const char *point = jimp->point;
if (!jimp__get_token(jimp)) return false;
if (jimp->token == JIMP_COMMA) return true;
Expand All @@ -249,11 +262,19 @@ void jimp_unknown_member(Jimp *jimp)

bool jimp_object_begin(Jimp *jimp)
{
return jimp__get_and_expect_token(jimp, JIMP_OCURLY);
if (!jimp__get_token(jimp)) return false;
if(jimp->token == JIMP_NULL) {
jimp->value_is_null = true;
} else if(jimp->token != JIMP_OCURLY) {
jimp_diagf(jimp, "ERROR: expected `%s` or `%s`, but got `%s`\n", jimp__token_kind(JIMP_OCURLY), jimp__token_kind(JIMP_NULL), jimp__token_kind(jimp->token));
return false;
}
return true;
}

bool jimp_object_member(Jimp *jimp)
{
if(jimp->value_is_null) return false;
const char *point = jimp->point;
if (!jimp__get_token(jimp)) return false;
if (jimp->token == JIMP_COMMA) {
Expand All @@ -274,34 +295,54 @@ bool jimp_object_member(Jimp *jimp)

bool jimp_object_end(Jimp *jimp)
{
if(jimp->value_is_null) {
jimp->value_is_null = false;
return true;
}
return jimp__get_and_expect_token(jimp, JIMP_CCURLY);
}

bool jimp_string(Jimp *jimp, const char **string)
bool jimp_string(Jimp *jimp, const char **string, const char*defaultt)
{
if (!jimp__get_and_expect_token(jimp, JIMP_STRING)) return false;
*string = strdup(jimp->string);
if (!jimp__get_token(jimp)) return false;
if(jimp->token == JIMP_NULL) {
*string = defaultt;
} else if(jimp->token == JIMP_STRING) {
*string = strdup(jimp->string);
} else {
jimp_diagf(jimp, "ERROR: expected `%s` or `%s`, but got `%s`\n", jimp__token_kind(JIMP_STRING), jimp__token_kind(JIMP_NULL), jimp__token_kind(jimp->token));
return false;
}
return true;
}

bool jimp_bool(Jimp *jimp, bool *boolean)
bool jimp_bool(Jimp *jimp, bool *boolean, bool defaultt)
{
jimp__get_token(jimp);
if (jimp->token == JIMP_TRUE) {
if (!jimp__get_token(jimp)) return false;
if(jimp->token == JIMP_NULL) {
*boolean = defaultt;
} else if (jimp->token == JIMP_TRUE) {
*boolean = true;
} else if (jimp->token == JIMP_FALSE) {
*boolean = false;
} else {
jimp_diagf(jimp, "ERROR: expected boolean, but got `%s`\n", jimp__token_kind(jimp->token));
jimp_diagf(jimp, "ERROR: expected boolean or `%s`, but got `%s`\n", jimp__token_kind(JIMP_NULL), jimp__token_kind(jimp->token));
return false;
}
return true;
}

bool jimp_number(Jimp *jimp, double *number)
bool jimp_number(Jimp *jimp, double *number, double defaultt)
{
if (!jimp__get_and_expect_token(jimp, JIMP_NUMBER)) return false;
*number = jimp->number;
if (!jimp__get_token(jimp)) return false;
if(jimp->token == JIMP_NULL) {
*number = defaultt;
} else if(jimp->token == JIMP_NUMBER) {
*number = jimp->number;
} else {
jimp_diagf(jimp, "ERROR: expected `%s` or `%s`, but got `%s`\n", jimp__token_kind(JIMP_NUMBER), jimp__token_kind(JIMP_NULL), jimp__token_kind(jimp->token));
return false;
}
return true;
}

Expand Down