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json: teach json builder "conditional" object fields
Quite often when we generate objects some fields should only be generated in some conditions. Let's add high-level support for that. Matching the existing JSON_BUILD_PAIR() this adds JSON_BUILD_PAIR_CONDITIONAL() which is very similar, but takes an additional parameter: a boolean condition. If "true" this acts like JSON_BUILD_PAIR(), but if false then the whole pair is suppressed. This sounds simply, but requires a tiny bit of complexity: when complex sub-variants are used in fields, then we also need to suppress them.
This commit is contained in:
Lennart Poettering
parent
2de6225314
commit
319a4f27c4
@ -2249,6 +2249,7 @@ typedef struct JsonStack {
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size_t n_elements, n_elements_allocated;
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unsigned line_before;
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unsigned column_before;
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size_t n_suppress; /* When building: if > 0, suppress this many subsequent elements. If == (size_t) -1, suppress all subsequent elements */
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} JsonStack;
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static void json_stack_release(JsonStack *s) {
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@ -2656,6 +2657,8 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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for (;;) {
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_cleanup_(json_variant_unrefp) JsonVariant *add = NULL;
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size_t n_subtract = 0; /* how much to subtract from current->n_suppress, i.e. how many elements would
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* have been added to the current variant */
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JsonStack *current;
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int command;
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@ -2679,9 +2682,13 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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p = va_arg(ap, const char *);
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r = json_variant_new_string(&add, p);
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if (r < 0)
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goto finish;
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if (current->n_suppress == 0) {
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r = json_variant_new_string(&add, p);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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if (current->expect == EXPECT_TOPLEVEL)
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current->expect = EXPECT_END;
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@ -2703,9 +2710,13 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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j = va_arg(ap, intmax_t);
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r = json_variant_new_integer(&add, j);
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if (r < 0)
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goto finish;
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if (current->n_suppress == 0) {
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r = json_variant_new_integer(&add, j);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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if (current->expect == EXPECT_TOPLEVEL)
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current->expect = EXPECT_END;
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@ -2727,9 +2738,13 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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j = va_arg(ap, uintmax_t);
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r = json_variant_new_unsigned(&add, j);
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if (r < 0)
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goto finish;
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if (current->n_suppress == 0) {
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r = json_variant_new_unsigned(&add, j);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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if (current->expect == EXPECT_TOPLEVEL)
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current->expect = EXPECT_END;
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@ -2751,9 +2766,13 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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d = va_arg(ap, long double);
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r = json_variant_new_real(&add, d);
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if (r < 0)
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goto finish;
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if (current->n_suppress == 0) {
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r = json_variant_new_real(&add, d);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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if (current->expect == EXPECT_TOPLEVEL)
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current->expect = EXPECT_END;
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@ -2775,9 +2794,13 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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b = va_arg(ap, int);
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r = json_variant_new_boolean(&add, b);
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if (r < 0)
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goto finish;
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if (current->n_suppress == 0) {
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r = json_variant_new_boolean(&add, b);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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if (current->expect == EXPECT_TOPLEVEL)
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current->expect = EXPECT_END;
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@ -2796,9 +2819,13 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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goto finish;
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}
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r = json_variant_new_null(&add);
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if (r < 0)
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goto finish;
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if (current->n_suppress == 0) {
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r = json_variant_new_null(&add);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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if (current->expect == EXPECT_TOPLEVEL)
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current->expect = EXPECT_END;
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@ -2816,12 +2843,16 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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goto finish;
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}
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/* Note that we don't care for current->n_suppress here, after all the variant is already
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* allocated anyway... */
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add = va_arg(ap, JsonVariant*);
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if (!add)
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add = JSON_VARIANT_MAGIC_NULL;
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else
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json_variant_ref(add);
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n_subtract = 1;
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if (current->expect == EXPECT_TOPLEVEL)
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current->expect = EXPECT_END;
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else if (current->expect == EXPECT_OBJECT_VALUE)
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@ -2841,13 +2872,17 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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l = va_arg(ap, const char *);
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if (!l)
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add = JSON_VARIANT_MAGIC_NULL;
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else {
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if (l) {
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/* Note that we don't care for current->n_suppress here, we should generate parsing
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* errors even in suppressed object properties */
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r = json_parse(l, &add, NULL, NULL);
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if (r < 0)
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goto finish;
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}
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} else
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add = JSON_VARIANT_MAGIC_NULL;
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n_subtract = 1;
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if (current->expect == EXPECT_TOPLEVEL)
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current->expect = EXPECT_END;
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@ -2881,6 +2916,10 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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stack[n_stack++] = (JsonStack) {
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.expect = EXPECT_ARRAY_ELEMENT,
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.n_suppress = current->n_suppress != 0 ? (size_t) -1 : 0, /* if we shall suppress the
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* new array, then we should
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* also suppress all array
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* members */
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};
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break;
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@ -2893,9 +2932,13 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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assert(n_stack > 1);
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r = json_variant_new_array(&add, current->elements, current->n_elements);
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if (r < 0)
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goto finish;
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if (current->n_suppress == 0) {
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r = json_variant_new_array(&add, current->elements, current->n_elements);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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json_stack_release(current);
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n_stack--, current--;
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@ -2912,9 +2955,13 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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l = va_arg(ap, char **);
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r = json_variant_new_array_strv(&add, l);
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if (r < 0)
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goto finish;
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if (current->n_suppress == 0) {
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r = json_variant_new_array_strv(&add, l);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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if (current->expect == EXPECT_TOPLEVEL)
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current->expect = EXPECT_END;
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@ -2948,6 +2995,10 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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stack[n_stack++] = (JsonStack) {
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.expect = EXPECT_OBJECT_KEY,
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.n_suppress = current->n_suppress != 0 ? (size_t) -1 : 0, /* if we shall suppress the
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* new object, then we should
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* also suppress all object
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* members */
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};
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break;
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@ -2961,9 +3012,13 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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assert(n_stack > 1);
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r = json_variant_new_object(&add, current->elements, current->n_elements);
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if (r < 0)
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goto finish;
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if (current->n_suppress == 0) {
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r = json_variant_new_object(&add, current->elements, current->n_elements);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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json_stack_release(current);
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n_stack--, current--;
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@ -2980,15 +3035,47 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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n = va_arg(ap, const char *);
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r = json_variant_new_string(&add, n);
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if (r < 0)
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if (current->n_suppress == 0) {
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r = json_variant_new_string(&add, n);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1;
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current->expect = EXPECT_OBJECT_VALUE;
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break;
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}
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case _JSON_BUILD_PAIR_CONDITION: {
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const char *n;
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bool b;
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if (current->expect != EXPECT_OBJECT_KEY) {
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r = -EINVAL;
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goto finish;
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}
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b = va_arg(ap, int);
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n = va_arg(ap, const char *);
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if (b && current->n_suppress == 0) {
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r = json_variant_new_string(&add, n);
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if (r < 0)
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goto finish;
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}
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n_subtract = 1; /* we generated one item */
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if (!b && current->n_suppress != (size_t) -1)
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current->n_suppress += 2; /* Suppress this one and the next item */
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current->expect = EXPECT_OBJECT_VALUE;
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break;
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}}
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if (add) {
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/* If a variant was generated, add it to our current variant, but only if we are not supposed to suppress additions */
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if (add && current->n_suppress == 0) {
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if (!GREEDY_REALLOC(current->elements, current->n_elements_allocated, current->n_elements + 1)) {
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r = -ENOMEM;
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goto finish;
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@ -2996,6 +3083,16 @@ int json_buildv(JsonVariant **ret, va_list ap) {
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current->elements[current->n_elements++] = TAKE_PTR(add);
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}
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/* If we are supposed to suppress items, let's subtract how many items where generated from that
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* counter. Except if the counter is (size_t) -1, i.e. we shall suppress an infinite number of elements
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* on this stack level */
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if (current->n_suppress != (size_t) -1) {
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if (current->n_suppress <= n_subtract) /* Saturated */
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current->n_suppress = 0;
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else
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current->n_suppress -= n_subtract;
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}
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}
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done:
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@ -177,6 +177,7 @@ enum {
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_JSON_BUILD_OBJECT_BEGIN,
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_JSON_BUILD_OBJECT_END,
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_JSON_BUILD_PAIR,
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_JSON_BUILD_PAIR_CONDITION,
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_JSON_BUILD_NULL,
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_JSON_BUILD_VARIANT,
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_JSON_BUILD_LITERAL,
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@ -192,6 +193,7 @@ enum {
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#define JSON_BUILD_ARRAY(...) _JSON_BUILD_ARRAY_BEGIN, __VA_ARGS__, _JSON_BUILD_ARRAY_END
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#define JSON_BUILD_OBJECT(...) _JSON_BUILD_OBJECT_BEGIN, __VA_ARGS__, _JSON_BUILD_OBJECT_END
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#define JSON_BUILD_PAIR(n, ...) _JSON_BUILD_PAIR, ({ const char *_x = n; _x; }), __VA_ARGS__
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#define JSON_BUILD_PAIR_CONDITION(c, n, ...) _JSON_BUILD_PAIR_CONDITION, ({ bool _x = c; _x; }), ({ const char *_x = n; _x; }), __VA_ARGS__
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#define JSON_BUILD_NULL _JSON_BUILD_NULL
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#define JSON_BUILD_VARIANT(v) _JSON_BUILD_VARIANT, ({ JsonVariant *_x = v; _x; })
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#define JSON_BUILD_LITERAL(l) _JSON_BUILD_LITERAL, ({ const char *_x = l; _x; })
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@ -316,6 +316,22 @@ static void test_build(void) {
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a = json_variant_unref(a);
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b = json_variant_unref(b);
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assert_se(json_build(&a, JSON_BUILD_OBJECT(
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JSON_BUILD_PAIR("x", JSON_BUILD_STRING("y")),
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JSON_BUILD_PAIR("z", JSON_BUILD_STRING("a")),
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JSON_BUILD_PAIR("b", JSON_BUILD_STRING("c"))
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)) >= 0);
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assert_se(json_build(&b, JSON_BUILD_OBJECT(
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JSON_BUILD_PAIR("x", JSON_BUILD_STRING("y")),
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JSON_BUILD_PAIR_CONDITION(false, "p", JSON_BUILD_STRING("q")),
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JSON_BUILD_PAIR_CONDITION(true, "z", JSON_BUILD_STRING("a")),
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JSON_BUILD_PAIR_CONDITION(false, "j", JSON_BUILD_ARRAY(JSON_BUILD_STRING("k"), JSON_BUILD_STRING("u"), JSON_BUILD_STRING("i"))),
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JSON_BUILD_PAIR("b", JSON_BUILD_STRING("c"))
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)) >= 0);
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assert_se(json_variant_equal(a, b));
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}
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static void test_source(void) {
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