Refactor json_unpack()
* Use the format string scanner from the previous commit (with the simpler separator skipping semantics) * Split json_vnunpack() to three separate functions for unpacking objects, arrays and "simple" values * Always return 0 on success, 1 on error This shaves around 100 more lines from the original implementation.
This commit is contained in:
Petri Lehtinen
parent
7f3018a4fb
commit
6d1f28f050
360
src/variadic.c
360
src/variadic.c
@ -175,81 +175,125 @@ static json_t *pack(scanner_t *s, va_list *ap)
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}
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}
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static int json_vnunpack(json_t *root, json_error_t *error, ssize_t size, const char *fmt, va_list *ap)
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static int unpack(scanner_t *s, json_t *root, va_list *ap);
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static int unpack_object(scanner_t *s, json_t *root, va_list *ap)
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{
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int rv = 0; /* Return value */
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int line = 1; /* Line number */
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int column = 1; /* Column */
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/* Position markers for arrays or objects */
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int array_index = 0;
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char *key = NULL;
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const char **s;
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/* Scanner variables */
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const char *tok = fmt;
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const char *etok;
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int etok_depth;
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json_t *obj;
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/* If we're successful, we need to know if the number of arguments
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* provided matches the number of JSON objects. We can do this by
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* counting the elements in every array or object we open up, and
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* decrementing the count as we visit their children. */
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int unvisited = 0;
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/* Skip whitespace at the beginning of the string. */
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while(size && *tok == ' ') {
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tok++;
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size--;
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column++;
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if(!json_is_object(root)) {
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set_error(s, "Expected object, got %i", json_typeof(root));
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return -1;
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}
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next_token(s);
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if(size <= 0) {
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jsonp_error_set(error, 1, 1, "Empty format string!");
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return -2;
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}
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while(s->token != '}') {
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const char *key;
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json_t *value;
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/* tok must contain either a container type, or a length-1 string for a
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* simple type. */
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if(*tok != '[' && *tok != '{')
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{
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/* Simple object. Permit trailing spaces, otherwise complain. */
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if((ssize_t)strspn(tok+1, " ") < size-1)
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{
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jsonp_error_set(error, 1, 1,
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"Expected a single object, got %i", size);
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if(!s->token) {
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set_error(s, "Unexpected end of format string");
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return -1;
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}
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switch(*tok)
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if(s->token != 's') {
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set_error(s, "Expected format 's', got '%c'\n", *s->fmt);
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return -1;
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}
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key = va_arg(*ap, const char *);
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if(!key) {
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set_error(s, "NULL object key");
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return -1;
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}
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next_token(s);
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value = json_object_get(root, key);
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if(unpack(s, value, ap))
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return -1;
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next_token(s);
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}
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return 0;
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}
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static int unpack_array(scanner_t *s, json_t *root, va_list *ap)
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{
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size_t i = 0;
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if(!json_is_array(root)) {
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set_error(s, "Expected array, got %d", json_typeof(root));
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return -1;
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}
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next_token(s);
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while(s->token != ']') {
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json_t *value;
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if(!s->token) {
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set_error(s, "Unexpected end of format string");
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return -1;
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}
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value = json_array_get(root, i);
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if(!value) {
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set_error(s, "Array index %lu out of range", (unsigned long)i);
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return -1;
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}
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if(unpack(s, value, ap))
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return -1;
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next_token(s);
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i++;
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}
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if(i != json_array_size(root)) {
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long diff = (long)json_array_size(root) - (long)i;
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set_error(s, "%li array items were not upacked", diff);
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return -1;
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}
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return 0;
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}
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static int unpack(scanner_t *s, json_t *root, va_list *ap)
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{
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switch(s->token)
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{
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case '{':
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return unpack_object(s, root, ap);
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case '[':
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return unpack_array(s, root, ap);
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case 's':
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{
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const char **str;
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if(!json_is_string(root))
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{
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jsonp_error_set(error, line, column,
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"Type mismatch! Object (%i) wasn't a string.",
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set_error(s, "Type mismatch! Object (%i) wasn't a string.",
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json_typeof(root));
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return -2;
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return -1;
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}
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s = va_arg(*ap, const char **);
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if(!s) {
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jsonp_error_set(error, line, column, "Passed a NULL string pointer!");
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return -2;
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str = va_arg(*ap, const char **);
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if(!str) {
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set_error(s, "Passed a NULL string pointer!");
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return -1;
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}
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*s = json_string_value(root);
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*str = json_string_value(root);
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return 0;
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}
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case 'i':
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if(!json_is_integer(root))
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{
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jsonp_error_set(error, line, column,
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"Type mismatch! Object (%i) wasn't an integer.",
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set_error(s, "Type mismatch! Object (%i) wasn't an integer.",
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json_typeof(root));
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return -2;
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return -1;
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}
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*va_arg(*ap, int*) = json_integer_value(root);
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return 0;
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@ -257,10 +301,9 @@ static int json_vnunpack(json_t *root, json_error_t *error, ssize_t size, const
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case 'b':
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if(!json_is_boolean(root))
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{
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jsonp_error_set(error, line, column,
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"Type mismatch! Object (%i) wasn't a boolean.",
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set_error(s, "Type mismatch! Object (%i) wasn't a boolean.",
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json_typeof(root));
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return -2;
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return -1;
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}
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*va_arg(*ap, int*) = json_is_true(root);
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return 0;
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@ -268,10 +311,9 @@ static int json_vnunpack(json_t *root, json_error_t *error, ssize_t size, const
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case 'f':
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if(!json_is_number(root))
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{
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jsonp_error_set(error, line, column,
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"Type mismatch! Object (%i) wasn't a real.",
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set_error(s, "Type mismatch! Object (%i) wasn't a real.",
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json_typeof(root));
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return -2;
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return -1;
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}
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*va_arg(*ap, double*) = json_number_value(root);
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return 0;
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@ -285,174 +327,19 @@ static int json_vnunpack(json_t *root, json_error_t *error, ssize_t size, const
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return 0;
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case 'n':
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/* Don't actually assign anything; we're just happy
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* the null turned up as promised in the format
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* string. */
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/* Don't assign, just validate */
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if(!json_is_null(root))
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{
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set_error(s, "Type mismatch! Object (%i) wasn't null.",
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json_typeof(root));
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return -1;
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}
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return 0;
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default:
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jsonp_error_set(error, line, column,
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"Unknown format character '%c'", *tok);
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set_error(s, "Unknown format character '%c'", s->token);
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return -1;
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}
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}
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/* Move past container opening token */
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tok++;
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while(tok-fmt < size) {
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switch(*tok) {
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case '\n':
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line++;
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column = 0;
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break;
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case ' ': /* Whitespace */
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break;
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case ',': /* Element spacer */
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if(key)
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{
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jsonp_error_set(error, line, column,
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"Expected KEY, got COMMA!");
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return -2;
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}
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break;
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case ':': /* Key/value separator */
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if(!key)
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{
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jsonp_error_set(error, line, column,
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"Got key/value separator without "
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"a key preceding it!");
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return -2;
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}
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if(!json_is_object(root))
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{
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jsonp_error_set(error, line, column,
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"Got a key/value separator "
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"(':') outside an object!");
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return -2;
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}
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break;
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case ']': /* Close array or object */
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case '}':
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if(tok-fmt + (ssize_t)strspn(tok+1, " ") != size-1)
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{
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jsonp_error_set(error, line, column,
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"Unexpected close-bracket '%c'", *tok);
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return -2;
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}
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if((*tok == ']' && !json_is_array(root)) ||
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(*tok == '}' && !json_is_object(root)))
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{
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jsonp_error_set(error, line, column,
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"Stray close-array '%c' character", *tok);
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return -2;
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}
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return unvisited;
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case '[':
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case '{':
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/* Find corresponding close bracket */
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etok = tok+1;
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etok_depth = 1;
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while(etok_depth) {
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if(!*etok || etok-fmt >= size) {
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jsonp_error_set(error, line, column,
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"Couldn't find matching close bracket for '%c'",
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*tok);
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return -2;
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}
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if(*tok == *etok)
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etok_depth++;
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else if(*tok == '[' && *etok == ']') {
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etok_depth--;
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break;
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} else if(*tok == '{' && *etok == '}') {
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etok_depth--;
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break;
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}
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etok++;
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}
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/* Recurse */
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if(json_is_array(root)) {
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rv = json_vnunpack(json_object_get(root, key),
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error, etok-tok+1, tok, ap);
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} else {
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rv = json_vnunpack(json_array_get(root, array_index++),
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error, etok-tok+1, tok, ap);
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}
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if(rv < 0) {
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/* error should already be set */
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error->column += column-1;
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error->line += line-1;
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return rv;
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}
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unvisited += rv;
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column += etok-tok;
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tok = etok;
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break;
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case 's':
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/* Handle strings specially, since they're used for both keys
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* and values */
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if(json_is_object(root) && !key)
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{
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/* It's a key */
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key = va_arg(*ap, char *);
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if(!key)
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{
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jsonp_error_set(error, line, column,
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"Refusing to handle a NULL key");
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return -2;
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}
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break;
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}
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/* Fall through */
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default:
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/* Fetch the element from the JSON container */
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if(json_is_object(root))
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obj = json_object_get(root, key);
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else
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obj = json_array_get(root, array_index++);
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if(!obj) {
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jsonp_error_set(error, line, column,
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"Array/object entry didn't exist!");
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return -1;
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}
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rv = json_vnunpack(obj, error, 1, tok, ap);
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if(rv != 0)
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return rv;
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break;
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}
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tok++;
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column++;
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}
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/* Whoops -- we didn't match the close bracket! */
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jsonp_error_set(error, line, column, "Missing close array or object!");
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return -2;
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}
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json_t *json_pack(json_error_t *error, const char *fmt, ...)
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@ -490,19 +377,36 @@ json_t *json_pack(json_error_t *error, const char *fmt, ...)
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int json_unpack(json_t *root, json_error_t *error, const char *fmt, ...)
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{
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scanner_t s;
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va_list ap;
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int rv;
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int result;
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jsonp_error_init(error, "");
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if(!fmt || !*fmt) {
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jsonp_error_set(error, 1, 1, "Null or empty format string!");
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return -2;;
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return -1;
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}
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s.error = error;
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s.fmt = fmt;
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s.line = 1;
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s.column = 0;
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next_token(&s);
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va_start(ap, fmt);
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rv = json_vnunpack(root, error, strlen(fmt), fmt, &ap);
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result = unpack(&s, root, &ap);
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va_end(ap);
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return rv;
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if(result)
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return -1;
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next_token(&s);
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if(s.token) {
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set_error(&s, "Garbage after format string");
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return -1;
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}
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return 0;
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}
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