#ifndef PARSER_H
#define PARSER_H

#include "util.h"
#include "tree.h"
#include "token.h"

/* Parser states. */
typedef enum PARSER_STATE {
   PARSER_STATE_BLOCK,
   PARSER_STATE_EXPR,
   PARSER_STATE_LINT,
   PARSER_STATE_LSTR,
   PARSER_STATE_TAG,
   PARSER_STATE_DARG,
   PARSER_STATE_CARG,
   PARSER_STATE_DEF,
   PARSER_STATE_CALL
} parser_state_t;

typedef struct PARSER {
   /* What the parser's looking at. */
   parser_state_t state;

   /* The token list being consumed. */
   token_t* token;
   
   /* The AST being produced. */
   tree_t* tree;
} parser_t;

/* Creates a new parser. */
parser_t* parser_init(token_t* token);

/* 
   Destroys a parser.
   - Does not free the token list.
   - Does not free the AST.
*/
void parser_destroy(parser_t* parser);

/* Step the parser forward by 1 token. */
int parser_nxt_token(parser_t* parser);

/* Get tree for first (implied) block. */
tree_t* parser_parse_init(parser_t* parser);

/* Get tree for a block. */
tree_t* parser_parse_block(parser_t* parser);

/* Get tree for a keyword. */
tree_t* parser_parse_kwd(parser_t* parser);

/* Get tree for an expression.*/
tree_t* parser_parse_expr(parser_t* parser);

/* Return the tree for an integer. */
tree_t* parser_parse_lint(parser_t* parser);

/* Return the tree for a string.  */
tree_t* parser_parse_lstr(parser_t* parser);

/* Return the tree for a call. */
tree_t* parser_parse_call(parser_t* parser);

/* Return the tree for a call's arguments. */
tree_t* parser_parse_carg(parser_t* parser);

/* Return the tree for a definition. */
tree_t* parser_parse_def(parser_t* parser);

/* Return the tree for a definition tag. */
tree_t* parser_parse_tag(parser_t* parser);

/* Return the tree for a definition's arguments. */
tree_t* parser_parse_darg(parser_t* parser);

/* 
   Check whether the current token matches the given type.
   - If it doesn't, return 0 and throw error.
*/
int parser_match(parser_t* parser, token_type_t type);

/* Steps the parser forward by one token, then check whether the new token matches the given type. */
int parser_nxt_token_match(parser_t* parser, token_type_t type);

/* Parse. */
void parser_parse(parser_t* parser);

/* Parse with the given parser. */
void parser_run(parser_t* parser);

#endif