Get something working

Signed-off-by: Slendi <slendi@socopon.com>

programs/dcfgq.c

@@ -0,0 +1,143 @@
+#include <dcfg.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef enum {
+	T_FIELD,
+	T_INDEX,
+} TokenType;
+
+typedef struct {
+	TokenType type;
+	union {
+		dcfg_StringView field;
+		size_t index;
+	} v;
+} Token;
+
+#define MAX_TOKENS 256
+
+static size_t tokenize(char const *query, Token *out)
+{
+	size_t count = 0;
+	size_t i = 0;
+	if (query[i] == '.')
+		i++;
+	while (query[i] && count < MAX_TOKENS) {
+		if (query[i] == '.') {
+			i++;
+			size_t start = i;
+			while (query[i] && query[i] != '.' && query[i] != '[')
+				i++;
+			out[count].type = T_FIELD;
+			out[count].v.field.data = query + start;
+			out[count].v.field.size = i - start;
+			count++;
+		} else if (query[i] == '[') {
+			i++;
+			char *end;
+			size_t idx = strtoul(query + i, &end, 10);
+			if (*end != ']') {
+				fprintf(stderr, "invalid index\n");
+				exit(1);
+			}
+			i = (size_t)(end - query) + 1;
+			out[count].type = T_INDEX;
+			out[count].v.index = idx;
+			count++;
+		} else {
+			size_t start = i;
+			while (query[i] && query[i] != '.' && query[i] != '[')
+				i++;
+			out[count].type = T_FIELD;
+			out[count].v.field.data = query + start;
+			out[count].v.field.size = i - start;
+			count++;
+		}
+	}
+	return count;
+}
+
+static void print_value(dcfg_Value *v)
+{
+	dcfg_StringView sv;
+	if (dcfg_serialize_value(v, &sv)) {
+		fwrite(sv.data, 1, sv.size, stdout);
+		free((void *)sv.data);
+		putchar('\n');
+	} else {
+		puts("null");
+	}
+}
+
+int main(int argc, char **argv)
+{
+	if (argc < 3) {
+		fprintf(stderr, "usage: %s <query> <file>\n", argv[0]);
+		return 1;
+	}
+	char const *query = argv[1];
+	char const *file = argv[2];
+
+	dcfg_Instance *inst = dcfg_make_instance(&(dcfg_InstanceCreateInfo) { 0 });
+	if (!inst) {
+		fprintf(stderr, "failed to create instance\n");
+		return 1;
+	}
+	dcfg_Value *root = dcfg_parse(inst, dcfg_SV(file));
+	if (!root) {
+		fprintf(stderr, "parse error: %s\n", dcfg_last_error(inst));
+		dcfg_destroy_instance(inst);
+		return 1;
+	}
+
+	Token toks[MAX_TOKENS];
+	size_t n = tokenize(query, toks);
+
+	dcfg_Value *evaled;
+	if (!dcfg_Value_evaluate_toplevel(root, &evaled, NULL, NULL, 0)) {
+		fprintf(stderr, "evaluation error: %s\n", dcfg_last_error(inst));
+		dcfg_destroy(root);
+		dcfg_destroy_instance(inst);
+		return 1;
+	}
+
+	dcfg_Value *cur = evaled;
+	for (size_t i = 0; i < n; i++) {
+		Token *t = &toks[i];
+		dcfg_Value *next = NULL;
+
+		if (t->type == T_FIELD) {
+			if (!dcfg_Value_get_object_field_ex(cur, t->v.field, &next, true)) {
+				fprintf(stderr, "no such field\n");
+				dcfg_destroy(evaled);
+				dcfg_destroy(root);
+				dcfg_destroy_instance(inst);
+				return 1;
+			}
+		} else {
+			if (!dcfg_Value_get_array_item_ex(cur, t->v.index, &next, true)) {
+				fprintf(stderr, "index out of bounds\n");
+				dcfg_destroy(evaled);
+				dcfg_destroy(root);
+				dcfg_destroy_instance(inst);
+				return 1;
+			}
+		}
+
+		if (cur != evaled)
+			dcfg_destroy(cur);
+
+		cur = next;
+	}
+	print_value(cur);
+	if (cur != evaled)
+		dcfg_destroy(cur);
+
+	dcfg_destroy(evaled);
+	dcfg_destroy(root);
+	dcfg_destroy_instance(inst);
+	return 0;
+}