Implement support for settings

Settings are a flat "dictionary" containing
paths to settings on the format:

<category>.<sub-category>.<setting>.

1 files changed, 133 insertions, 0 deletions

diff --git a/src/settings.h b/src/settings.h
new file mode 100644
index 0000000..8d6f1f2
--- /dev/null
+++ b/src/settings.h
@@ -0,0 +1,133 @@
+#include "command.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/**
+ * The type of setting value.
+ */
+enum setting_type {
+  /** String setting. */
+  Setting_String = 0,
+
+  /** Number setting (a signed 64 bit integer). */
+  Setting_Number,
+
+  /** Boolean setting. */
+  Setting_Bool,
+};
+
+/**
+ * Value for a setting.
+ */
+struct setting_value {
+  /** Type of setting. */
+  enum setting_type type;
+
+  union {
+    /** String setting. */
+    char *string_value;
+
+    /** Real number setting. */
+    int64_t number_value;
+
+    /** Boolean setting value. */
+    bool bool_value;
+  };
+};
+
+/**
+ * A single setting.
+ *
+ * A setting has a "path", denoted by a string
+ * containing a number (0-) of dots.
+ * Example: editor.tab-width.
+ */
+struct setting {
+
+  /** Path of the setting. */
+  char path[128];
+
+  /** Hashed path that can be used for equality checks. */
+  uint32_t hash;
+
+  /** Value of the setting. */
+  struct setting_value value;
+};
+
+/**
+ * A collection of settings.
+ */
+struct settings {
+  /** Settings */
+  struct setting *settings;
+
+  /** Number of settings currently in collection. */
+  uint32_t nsettings;
+
+  /** Current capacity of collection. */
+  uint32_t capacity;
+};
+
+/**
+ * Initialize the global collection of settings.
+ *
+ * @param initial_capacity Initial capacity of the settings collection.
+ * @returns Nothing, the settings collection is a global instance.
+ */
+void settings_init(uint32_t initial_capacity);
+
+/**
+ * Destroy the global collection of settings.
+ */
+void settings_destroy();
+
+/**
+ * Register a new setting.
+ *
+ * @param path The path of the new setting on
+ * the form <category>.<sub-category>.<setting-name>.
+ * @param default_value The default value for the setting.
+ * All settings are required to declare a default value.
+ */
+void settings_register_setting(const char *path,
+                               struct setting_value default_value);
+
+/**
+ * Retrieve a single setting by path.
+ *
+ * @param path The exact path of the setting on
+ * the form <category>.<sub-category>.<setting-name>.
+ * @returns A pointer to the setting if found, NULL otherwise.
+ */
+struct setting *settings_get(const char *path);
+
+/**
+ * Retrieve a collection of settings by prefix
+ *
+ * @param prefix Path prefix for the settings to retrieve.
+ * @param settings_out Pointer to an array that will be modified to point to the
+ * result.
+ * @param nsettings_out Pointer to an integer that will be set to the number of
+ * settings pointers in the result.
+ */
+void settings_get_prefix(const char *prefix, struct setting **settings_out[],
+                         uint32_t *nsettings_out);
+
+/**
+ * Set a value for a setting.
+ *
+ * @param path The exact path of the setting on
+ * the form <category>.<sub-category>.<setting-name>.
+ * @param value The new value of the setting. The type has to match the declared
+ * type for the setting. If not, the new value is ignored.
+ */
+void settings_set(const char *path, struct setting_value value);
+
+int32_t settings_get_cmd(struct command_ctx ctx, int argc, const char *argv[]);
+int32_t settings_set_cmd(struct command_ctx ctx, int argc, const char *argv[]);
+
+static struct command SETTINGS_COMMANDS[] = {
+    {.name = "set", .fn = settings_set_cmd},
+    {.name = "get", .fn = settings_get_cmd},
+};