#ifndef syntax_h
#define syntax_h
#include "lexer.h"
#include "intern.h"
#include "scope.h"
#include "bitset.h"
#include "builtins.h"
#include <stdbool.h>
typedef struct expr expr_t;

typedef struct {
  expr_t *expr;
  size_t bound_vars;
} pattern_t;

struct expr {
  enum {
    EXPR_CALL,
    EXPR_VAR,
    EXPR_PAT_IDENT,
    EXPR_CONSTRUCTOR,
    EXPR_INT_LIT,
    EXPR_FLOAT_LIT,
    EXPR_LET_BINDING,
    EXPR_STRING_LIT,
    EXPR_TUPLE,
    EXPR_LAMBDA,
    EXPR_LAMBDA_COMPILED,
    EXPR_GROUP,
    EXPR_ALT,
    EXPR_SEQ,
    EXPR_BUILTIN,
  } tag;
  source_t *source;
  pos_t pos;
  union {
    struct {
        expr_t *callee;
        expr_t **arguments;
        size_t nargs;
    } call;
    struct {
      expr_t *try;
      expr_t *orelse;
    } alt;
    struct {
      expr_t *first;
      expr_t *then;
    } seq;
    struct {
      pattern_t pattern;
      expr_t *expr;
      expr_t *in;
    } let_binding;
    de_bruijn_t var;
    builtin_func_t *builtin;
    intern_t ident;
    intern_t constructor;
    long int_lit;
    double float_lit;
    char *string_lit;
    struct {
      size_t args;
      expr_t *body;   
      bitset_t *mask;
      size_t num_lets;      
    } lambda;
    struct {
      expr_t** clauses;
      size_t nclauses;
    } group;
    struct {
      expr_t** elements;
      size_t nelements;
    } tuple;
    struct {
      expr_t** patterns;
      size_t npatterns;
      expr_t *body;
    } lambda_raw;
  } as;
};


expr_t *syntax_parse_expr(lexer_t *lexer, builtins_t *builtins, intern_table_t *table);

/* returns the amount of local binding slots required to evaluate this expression */
size_t syntax_expr_required_locals(expr_t *it);
void syntax_expr_free(expr_t *it);
void syntax_dump_expr(expr_t *it);
#endif