Update README

README.md

@@ -1,30 +1,117 @@
 
 # C JSON Parser
 
-Just for fun.
+Just a simple project to practice writing parsers.
+Not guaranteed to be safe or efficient.
 
-Parses json values into structs containing type information and data.
-Arrays are null-terminated arrays of pointers to json values.
-Objects are represented with a poorly written map implementation.
-Remaining data types are represented with native C types.
+## Usage
 
-# Usage
-
-##  Compile
-
-**option 1** build (debug build):
-```sh
-make
-```
-
-**option 2** build (release build):
+###  Compile
+build (release build):
 ```sh
 make BUILD=release
 ```
+To make a debug build just run `make`.
 
-## Run
+### Run
 
 ```sh
 ./bin/{release|debug}/json_parser
 ```
 
+## Limitations
+
+Does not support unicode.
+
+## Implementation
+
+Parsed JSON values are stored as structs containing type information and data.
+
+```c
+enum json_type { object, array, string, number, boolean, null };
+
+struct json_value {
+    enum json_type type;
+
+    union {
+        obj_t*              object;
+        struct json_value** array;
+        char*               string;
+        bool                boolean;
+        int64_t             number;
+    };
+};
+```
+
+### Types
+
+#### JSON Arrays
+
+Array values have the type field set to `(enum json_type) array`
+
+JSON Arrays are stored as null-terminated `json_value*` arrays,
+`struct json_value**`, in `json_value.array`
+
+
+#### JSON Numbers
+
+Number values have the type field set to `(enum json_type) number`
+
+Numbers are stored as `double` values in `json_value.number`
+
+(The JSON specification doesn't strictly specify a maximum value, 
+but `double` is sufficient for parsing almost all JSON data.)
+
+
+#### JSON Strings
+
+Strings have the type field set to `(enum json_type) string`
+
+Strings are stored as null-terminated char arrays, `char*`, in `json_value.string`
+
+
+#### JSON Booleans
+
+Boolean values have the type field set to `(enum json_type) boolean`
+
+The values are stored as `bool` in `json_value.boolean`
+
+
+#### JSON Null
+
+Null values have type field set to `(enum json_type) null`.
+
+
+#### JSON Objects
+
+Object values have the type field set to `(enum json_type) object`
+
+They are stored using a poorly written map implementation with the type `obj_t`
+in `json_value.object`
+
+##### obj\_t
+
+```c
+typedef struct obj_entry {
+    char const* key;
+    struct json_value* val;
+    struct obj_entry* next;
+} * __p_obj_entry;
+
+typedef __p_obj_entry obj_t[OBJ_SIZE]; // OBJ_SIZE=1024
+```
+
+##### obj\_t methods
+
+`void* obj_at(obj_t m, char* key)`
+
+Returns a pointer to a value for the given key.
+
+`bool obj_insert(obj_t m, char* const key, struct json_value* value)`
+
+Insert a key-value pair
+
+`void obj_delete(obj_t m)`
+
+Free memory allocated for object
+