/*
  Copyright (C) 2019 Leo Tenenbaum.
  This file is part of toc. toc is distributed under version 3 of the GNU General Public License, without any warranty whatsoever.
  You should have received a copy of the GNU General Public License along with toc. If not, see <https://www.gnu.org/licenses/>.
*/
static bool parse_expr(Parser *p, Expression *e, Token *end);
static bool parse_stmt(Parser *p, Statement *s);
enum {
	  PARSE_DECL_ALLOW_CONST_WITH_NO_EXPR = 0x01,
	  PARSE_DECL_ALLOW_SEMI_CONST = 0x02,
};
static bool parse_decl(Parser *p, Declaration *d, DeclEndKind ends_with, uint16_t flags);
static bool parse_decl_list(Parser *p, Declaration **decls, DeclEndKind decl_end);

static bool is_decl(Tokenizer *t);
static inline bool ends_decl(Token *t, DeclEndKind ends_with);

static bool fn_has_any_const_params(FnExpr *f) {
	arr_foreach(f->params, Declaration, param)
		if (param->flags & (DECL_IS_CONST | DECL_SEMI_CONST))
			return true;
	return false;
}

static const char *expr_kind_to_str(ExprKind k) {
	switch (k) {
	case EXPR_LITERAL_FLOAT: return "float literal";
	case EXPR_LITERAL_INT: return "integer literal";
	case EXPR_LITERAL_STR: return "string literal";
	case EXPR_LITERAL_BOOL: return "boolean literal";
	case EXPR_LITERAL_CHAR: return "character literal";
	case EXPR_IF: return "if expression";
	case EXPR_WHILE: return "while expression";
	case EXPR_EACH: return "each expression";
	case EXPR_CALL: return "function call";
	case EXPR_C: return "c code";
	case EXPR_DSIZEOF: return "#sizeof";
	case EXPR_DALIGNOF: return "#alignof";
	case EXPR_NEW: return "new expression";
	case EXPR_CAST: return "cast expression";
	case EXPR_UNARY_OP: return "unary operator";
	case EXPR_BINARY_OP: return "binary operator";
	case EXPR_FN: return "function expression";
	case EXPR_TUPLE: return "tuple";
	case EXPR_BLOCK: return "block";
	case EXPR_IDENT: return "identifier";
	case EXPR_SLICE: return "slice";
	case EXPR_TYPE: return "type";
	case EXPR_VAL: return "value";
	}
	assert(0);
	return "";
}

static const char *unary_op_to_str(UnaryOp u) {
	switch (u) {
	case UNARY_MINUS: return "-";
	case UNARY_ADDRESS: return "&";
	case UNARY_DEREF: return "*";
	case UNARY_NOT: return "!";
	case UNARY_DEL: return "del";
	case UNARY_LEN: return "len";
	}
	assert(0);
	return "";
}

static const char *binary_op_to_str(BinaryOp b) {
	switch (b) {
	case BINARY_ADD: return "+";
	case BINARY_SUB: return "-";
	case BINARY_MUL: return "*";
	case BINARY_DIV: return "/";
	case BINARY_SET: return "=";
	case BINARY_SET_ADD: return "+=";
	case BINARY_SET_SUB: return "-=";
	case BINARY_SET_MUL: return "*=";
	case BINARY_SET_DIV: return "/=";
	case BINARY_AT_INDEX: return "[]";
	case BINARY_LT: return "<";
	case BINARY_LE: return "<=";
	case BINARY_GT: return ">";
	case BINARY_GE: return ">=";
	case BINARY_EQ: return "==";
	case BINARY_NE: return "!=";
	case BINARY_DOT: return ".";
	}
	assert(0);
	return "";
}

static bool type_builtin_is_signed(BuiltinType b) {
	switch (b) {
	case BUILTIN_I8:
	case BUILTIN_I16:
	case BUILTIN_I32:
	case BUILTIN_I64:
		return true;
	default: return false;
	}
}

static bool type_builtin_is_int(BuiltinType b) {
	switch (b) {
	case BUILTIN_I8:
	case BUILTIN_I16:
	case BUILTIN_I32:
	case BUILTIN_I64:
	case BUILTIN_U8:
	case BUILTIN_U16:
	case BUILTIN_U32:
	case BUILTIN_U64:
		return true;
	default: return false;
	}
}

static bool type_builtin_is_float(BuiltinType b) {
	switch (b) {
	case BUILTIN_F32:
	case BUILTIN_F64:
		return true;
	default: return false;
	}
}

static bool type_builtin_is_numerical(BuiltinType b) {
	return type_builtin_is_int(b) || type_builtin_is_float(b);
}


/* returns -1 on failure */
static int kw_to_builtin_type(Keyword kw) {
	switch (kw) {
	case KW_I8: return BUILTIN_I8;
	case KW_I16: return BUILTIN_I16;
	case KW_I32: return BUILTIN_I32;
	case KW_I64: return BUILTIN_I64;
	case KW_INT: return BUILTIN_I64;
	case KW_U8: return BUILTIN_U8;
	case KW_U16: return BUILTIN_U16;
	case KW_U32: return BUILTIN_U32;
	case KW_U64: return BUILTIN_U64;
	case KW_FLOAT: return BUILTIN_F32;
	case KW_F32: return BUILTIN_F32;
	case KW_F64: return BUILTIN_F64;
	case KW_BOOL: return BUILTIN_BOOL;
	case KW_CHAR: return BUILTIN_CHAR;
	default: return -1;
	}
	return -1;
}

static Keyword builtin_type_to_kw(BuiltinType t) {
	switch (t) {
	case BUILTIN_I8: return KW_I8;
	case BUILTIN_I16: return KW_I16;
	case BUILTIN_I32: return KW_I32;
	case BUILTIN_I64: return KW_I64;
	case BUILTIN_U8: return KW_U8;
	case BUILTIN_U16: return KW_U16;
	case BUILTIN_U32: return KW_U32;
	case BUILTIN_U64: return KW_U64;
	case BUILTIN_F32: return KW_F32;
	case BUILTIN_F64: return KW_F64;
	case BUILTIN_BOOL: return KW_BOOL;
	case BUILTIN_CHAR: return KW_CHAR;
	}
	assert(0);
	return KW_COUNT;
}

/* TODO: DELME */
static void fprint_expr(FILE *out, Expression *expr);


/* returns the number of characters written, not including the null character */
static size_t type_to_str_(Type *t, char *buffer, size_t bufsize) {
	/* if ((t->flags & TYPE_IS_RESOLVED) && t->was_expr) { */
	/* 	/\* TODO: improve this (see also: case TYPE_EXPR) *\/ */
	/* 	return str_copy(buffer, bufsize, "<type expression>"); */
	/* } */
	switch (t->kind) {
	case TYPE_VOID:
		return str_copy(buffer, bufsize, "void");
	case TYPE_UNKNOWN:
		return str_copy(buffer, bufsize, "???");
	case TYPE_BUILTIN: {
		const char *s = keywords[builtin_type_to_kw(t->builtin)];
		return str_copy(buffer, bufsize, s);
	}
	case TYPE_FN: {
		size_t written = str_copy(buffer, bufsize, "fn (");
		Type *ret_type = t->fn.types;
		Type *param_types = ret_type + 1;
		size_t nparams = arr_len(t->fn.types) - 1;
		for (size_t i = 0; i < nparams; ++i) {
			if (i > 0)
				written += str_copy(buffer + written, bufsize - written, ", ");
			if (t->fn.constness) {
				switch (t->fn.constness[i]) {
				case CONSTNESS_NO: break;
				case CONSTNESS_SEMI:
					written += str_copy(buffer + written, bufsize - written, ":::");
					break;
				case CONSTNESS_YES:
					written += str_copy(buffer + written, bufsize - written, "::");
					break;
				}
			}

			written += type_to_str_(&param_types[i], buffer + written, bufsize - written);
		}
		written += str_copy(buffer + written, bufsize - written, ")");
		if (ret_type->kind != TYPE_VOID) {
			written += str_copy(buffer + written, bufsize - written, " ");
			written += type_to_str_(ret_type, buffer + written, bufsize - written);
		}
		return written;
	}
	case TYPE_STRUCT: {
		size_t written = str_copy(buffer, bufsize, "struct { ");
		arr_foreach(t->struc->fields, Field, f) {
			written += type_to_str_(f->type, buffer + written, bufsize - written);
			written += str_copy(buffer + written, bufsize - written, "; ");
		}
		written += str_copy(buffer + written, bufsize - written, " }");
		return written;
	}
	case TYPE_ARR: {
		size_t written = str_copy(buffer, bufsize, "[");
		if (t->flags & TYPE_IS_RESOLVED) {
			snprintf(buffer + written, bufsize - written, "%"PRIu64, t->arr.n);
			written += strlen(buffer + written);
		} else {
			written += str_copy(buffer + written, bufsize - written, "N");
		}
		written += str_copy(buffer + written, bufsize - written, "]");
		written += type_to_str_(t->arr.of, buffer + written, bufsize - written);
		return written;
	}
	case TYPE_SLICE: {
		size_t written = str_copy(buffer, bufsize, "[");
		written += str_copy(buffer + written, bufsize - written, "]");
		written += type_to_str_(t->slice, buffer + written, bufsize - written);
		return written;
	}
	case TYPE_TUPLE: {
		size_t written = str_copy(buffer, bufsize, "(");
		arr_foreach(t->tuple, Type, child) {
			if (child != t->tuple)
				written += str_copy(buffer + written, bufsize - written, ", ");
			written += type_to_str_(child, buffer + written, bufsize - written);
		}
		written += str_copy(buffer + written, bufsize - written, ")");
		return written;
	}
	case TYPE_PTR: {
		size_t written = str_copy(buffer, bufsize, "&");
		written += type_to_str_(t->ptr, buffer + written, bufsize - written);
		return written;
	}
	case TYPE_TYPE:
		return str_copy(buffer, bufsize, "<type>");
	case TYPE_EXPR:
		/* TODO: improve this... we're gonna need expr_to_str ): */
		return str_copy(buffer, bufsize, "<type expression>");
	}

	assert(0);
	return 0;
}

/* return value should be freed by caller */
static char *type_to_str(Type *t) {
	/* TODO allow types >255 chars */
	char *ret = err_malloc(256);
	type_to_str_(t, ret, 256);
	return ret;
}

static inline void *parser_arr_add_(Parser *p, void **a, size_t sz) {
	return arr_adda_(a, sz, p->allocr);
}

#define parser_arr_add(p, a) parser_arr_add_(p, (void **)(a), sizeof **(a))

static inline void *parser_malloc(Parser *p, size_t bytes) {
	return allocr_malloc(p->allocr, bytes);
}

/* 
   allocate a new expression.
*/
static inline Expression *parser_new_expr(Parser *p) {
	return parser_malloc(p, sizeof(Expression));
}

typedef enum {
	  EXPR_CAN_END_WITH_COMMA = 0x01, /* a comma could end the expression */
	  EXPR_CAN_END_WITH_LBRACE = 0x02,
	  EXPR_CAN_END_WITH_COLON = 0x04,
	  EXPR_CAN_END_WITH_DOTDOT = 0x08,
	  EXPR_CAN_END_WITH_EQ = 0x10,
	  /* note that parse_type uses -1 for this */
} ExprEndFlags;

static Token *expr_find_end(Parser *p, ExprEndFlags flags)  {
	Tokenizer *t = p->tokr;
	int paren_level = 0;
	int brace_level = 0;
	int square_level = 0;
	Token *token = t->token;
	bool could_be_vbs = false; /* could this be a void block statement (whose semicolons can be omitted)? e.g. {x := 5;} */
	while (1) {
		if (token->kind == TOKEN_KW) {
			bool all_levels_0 = paren_level == 0 && brace_level == 0 && square_level == 0;
			switch (token->kw) {
			case KW_COMMA:
				if ((flags & EXPR_CAN_END_WITH_COMMA) && all_levels_0)
					return token;
				break;
			case KW_LPAREN:
				++paren_level;
				break;
			case KW_RPAREN:
				--paren_level;
				if (paren_level < 0)
					return token;
				break;
			case KW_LSQUARE:
				++square_level;
				break;
			case KW_RSQUARE:
			    --square_level;
				if (square_level < 0)
					return token;
				break;
			case KW_LBRACE:
				if ((flags & EXPR_CAN_END_WITH_LBRACE) && square_level == 0 && paren_level == 0)
					return token;
				++brace_level;
				could_be_vbs = true;
				break;
			case KW_RBRACE:
				--brace_level;
				if (paren_level == 0 && brace_level == 0 && square_level == 0
					&& could_be_vbs && !token_is_kw(token + 1, KW_RPAREN)) {
					/* if there's an else/elif, the expr must continue */
					if (!(token_is_kw(token + 1, KW_ELSE) || token_is_kw(token + 1, KW_ELIF)))
						return token + 1; /* token afer } is end */
				}
				if (brace_level < 0)
					return token;
				break;
			case KW_SEMICOLON:
				if (brace_level == 0)
					return token;
				could_be_vbs = true;
				break;
			case KW_DOTDOT:
				if (all_levels_0 && (flags & EXPR_CAN_END_WITH_DOTDOT))
					return token;
				break;
			case KW_EQ:
				if (all_levels_0 && (flags & EXPR_CAN_END_WITH_EQ))
					return token;
				break;
			case KW_COLON:
				if ((flags & EXPR_CAN_END_WITH_COLON) && all_levels_0)
					return token;
			default: break;
			}
			if (token->kw != KW_RBRACE && token->kw != KW_SEMICOLON && token->kw != KW_LBRACE)
				could_be_vbs = false;
		} else {
			could_be_vbs = false;
		}
		if (token->kind == TOKEN_EOF) {
			if (brace_level > 0) {
				tokr_err(t, "Opening brace { was never closed."); /* FEATURE: Find out where this is */
			} else if (paren_level > 0) {
				tokr_err(t, "Opening parenthesis ( was never closed.");
			} else if (square_level > 0) {
				tokr_err(t, "Opening square bracket [ was never closed.");
			} else {
				tokr_err(t, "Could not find end of expression (did you forget a semicolon?).");
				/* FEATURE: improve err message */
			}
			t->token = token; /* don't try to continue */
			return NULL;
		}
		++token;
	}
}

/* parses, e.g. "(3, 5, foo)" */
static bool parse_args(Parser *p, Argument **args) {
	Tokenizer *t = p->tokr;
	Token *start = t->token;
	assert(token_is_kw(start, KW_LPAREN));
	*args = NULL;
	++t->token; /* move past ( */
	if (!token_is_kw(t->token, KW_RPAREN)) {
		/* non-empty arg list */
		while (1) {
			if (t->token->kind == TOKEN_EOF) {
				tokr_err(t, "Expected argument list to continue.");
				info_print(start->where, "This is where the argument list starts.");
				return false;
			}
			Argument *arg = parser_arr_add(p, args);
			arg->where = t->token->where;
			/* named arguments */
			if (t->token->kind == TOKEN_IDENT && token_is_kw(t->token + 1, KW_EQ)) {
			    arg->name = t->token->ident;
				t->token += 2;
			} else {
				arg->name = NULL;
			}
			if (!parse_expr(p, &arg->val, expr_find_end(p, EXPR_CAN_END_WITH_COMMA))) {
				return false;
			}
			if (token_is_kw(t->token, KW_RPAREN))
				break;
			assert(token_is_kw(t->token, KW_COMMA));
			++t->token;	/* move past , */
		}
	}
	++t->token;	/* move past ) */
	return true;
}

static bool parse_type(Parser *p, Type *type) {
	Tokenizer *t = p->tokr;
	type->where = t->token->where;
	type->flags = 0;
	switch (t->token->kind) {
	case TOKEN_KW:
		type->kind = TYPE_BUILTIN;
	    {
			int b = kw_to_builtin_type(t->token->kw);
			if (b != -1) {
				type->builtin = (BuiltinType)b;
				++t->token;
				break;
			}
		}
		/* Not a builtin */
		if (t->token->kw == KW_TYPE) {
			type->kind = TYPE_TYPE;
			++t->token;
			break;
		}
		switch (t->token->kw) {
		case KW_FN: {
			/* function type */
			type->kind = TYPE_FN;
			type->fn.types = NULL;
			type->fn.constness = NULL;
			++t->token;
			if (!token_is_kw(t->token, KW_LPAREN)) {
				tokr_err(t, "Expected ( to follow fn.");
				return false;
			}
			parser_arr_add(p, &type->fn.types); /* add return type */
			++t->token;
			if (!token_is_kw(t->token, KW_RPAREN)) {
				while (1) {
					Type *param_type = parser_arr_add(p, &type->fn.types);
					if (!parse_type(p, param_type)) return false;
					if (param_type->kind == TYPE_TUPLE) {
						err_print(param_type->where, "Functions cannot have tuples as parameters.");
						return false;
					}
					if (token_is_kw(t->token, KW_RPAREN))
						break;
					if (!token_is_kw(t->token, KW_COMMA)) {
						tokr_err(t, "Expected , to continue function type parameter list.");
						return false;
					}
					++t->token; /* move past , */
				}
			}
			++t->token;	/* move past ) */
			Type *ret_type = type->fn.types;
			/* if there's a symbol that isn't [, (, or &, that can't be the start of a type */
			if ((t->token->kind == TOKEN_KW
				 && t->token->kw <= KW_LAST_SYMBOL
				 && t->token->kw != KW_LSQUARE
				 && t->token->kw != KW_LPAREN
				 && t->token->kw != KW_AMPERSAND)
				|| t->token->kw == KW_AS) {
				ret_type->kind = TYPE_VOID;
				ret_type->flags = 0;
			} else {
				if (!parse_type(p, ret_type))
					return false;
			}
			break;
		}
		case KW_LSQUARE: {
			/* array/slice */
			type->where = t->token->where;
			type->kind = TYPE_ARR;
			++t->token;	/* move past [ */
			if (token_is_kw(t->token, KW_RSQUARE)) {
				/* slice */
				type->kind = TYPE_SLICE;
				type->slice = parser_malloc(p, sizeof *type->slice);
				++t->token; /* move past ] */
				if (!parse_type(p, type->slice)) return false;
				if (type->slice->kind == TYPE_TUPLE) {
					err_print(type->where, "You cannot have a slice of tuples.");
					return false;
				}
				break;
			}
			Token *end = expr_find_end(p, 0);
			type->arr.n_expr = parser_new_expr(p);
			if (!parse_expr(p, type->arr.n_expr, end)) return false;
			t->token = end + 1;	/* go past ] */
			type->arr.of = parser_malloc(p, sizeof *type->arr.of);
			if (!parse_type(p, type->arr.of)) return false;
			if (type->arr.of->kind == TYPE_TUPLE) {
				err_print(type->where, "You cannot have an array of tuples.");
				return false;
			}
		} break;
		case KW_LPAREN:
			/* tuple! */
			type->kind = TYPE_TUPLE;
		    type->tuple = NULL;
			++t->token;	/* move past ( */
			while (1) {
				Type *child = parser_arr_add(p, &type->tuple);
				if (!parse_type(p, child)) return false;
				if (child->kind == TYPE_TUPLE) {
					err_print(child->where, "Tuples cannot contain tuples.");
					return false;
				}
				if (token_is_kw(t->token, KW_RPAREN)) { /* we're done with the tuple */
					++t->token;	/* move past ) */
					break;
				}
				if (token_is_kw(t->token, KW_COMMA)) {
					++t->token;	/* move past , */
					continue;
				} else {
					tokr_err(t, "Expected , to list next tuple type or ) to end tuple type.");
					return false;
				}
			}
			break;
		case KW_AMPERSAND:
			/* pointer */
			type->kind = TYPE_PTR;
			type->ptr = parser_malloc(p, sizeof *type->ptr);
			++t->token;	/* move past & */
			if (!parse_type(p, type->ptr)) return false;
			if (type->ptr->kind == TYPE_TUPLE) {
				err_print(type->ptr->where, "You cannot have a pointer to a tuple.");
				return false;
			}
			break;
		case KW_STRUCT:
			/* struct */
			type->kind = TYPE_STRUCT;
			type->struc = parser_malloc(p, sizeof *type->struc);
			type->struc->flags = 0;
			/* help cgen out */
			type->struc->c.name = NULL;
			type->struc->c.id = 0;
			type->struc->fields = NULL;
			++t->token;
			if (!token_is_kw(t->token, KW_LBRACE)) {
				err_print(t->token->where, "Expected { or ( to follow struct.");
				return false;
			}
			++t->token;
			{
				while (!token_is_kw(t->token, KW_RBRACE)) {
					Declaration field_decl;
					if (!parse_decl(p, &field_decl, DECL_END_SEMICOLON, 0)) {
						return false;
					}
					if (field_decl.flags & DECL_IS_CONST) {
						/* TODO */
						err_print(field_decl.where, "Constant struct members are not supported (yet).");
						return false;
					}
					if (field_decl.flags & DECL_HAS_EXPR) {
						err_print(field_decl.where, "struct members cannot have initializers.");
						return false;
					}
					long idx = 0;
					arr_foreach(field_decl.idents, Identifier, fident) {
						Type *ftype = field_decl.type.kind == TYPE_TUPLE ? &field_decl.type.tuple[idx] : &field_decl.type;
						Field *f = parser_arr_add(p, &type->struc->fields);
						f->name = *fident;
						f->type = parser_malloc(p, sizeof *f->type);
						*f->type = *ftype;
						++idx;
					}
				}
				++t->token;
			}
			break;
		default:
			tokr_err(t, "Unrecognized type.");
			return false;
		}
		break;
	default:
		/* TYPE_EXPR */
		if (parse_expr(p, type->expr = parser_new_expr(p),
					   expr_find_end(p, (ExprEndFlags)-1 /* end as soon as possible */))) {
			type->kind = TYPE_EXPR;
		} else {
			tokr_err(t, "Unrecognized type.");
			return false;
		}
	}
	return true;
	
}

/* 
is the thing we're looking at definitely a type, as opposed to an expression? 
if end is not NULL, it is set to the token one past the last one in the type,
assuming it's successful
*/
static bool parser_is_definitely_type(Parser *p, Token **end) {
	Tokenizer *t = p->tokr;
	Token *start = t->token;
	bool ret = false;
    do {
	continu:
		switch (t->token->kind) {
		case TOKEN_KW:
			switch (t->token->kw) {
			case KW_STRUCT:
				ret = true;
				if (end) {
					int level = 1;
					t->token += 2; /* skip struct { */
					while (t->token->kind != TOKEN_EOF) {
						if (t->token->kind == TOKEN_KW) switch (t->token->kw) {
							case KW_LBRACE:
								++level;
								break;
							case KW_RBRACE:
								--level;
								if (level == 0) goto end;
								break;
							default: break;
							}
						++t->token;
					}
				}
			    break;
			case KW_LSQUARE:
				ret = true;
				if (end) {
					int level = 1;
					++t->token;
					while (t->token->kind != TOKEN_EOF) {
						if (t->token->kind == TOKEN_KW) switch (t->token->kw) {
							case KW_LSQUARE:
								++level;
								break;
							case KW_RSQUARE:
								--level;
								if (level == 0) {
									if (end) {
										++t->token;
										parser_is_definitely_type(p, &t->token); /* move to end of type */
									}
									goto end;
								}
								break;
							default: break;
							}
						++t->token;
					}
				}
				break;
			case KW_LPAREN: {
				Token *child_end;
				++t->token;
				ret = false;
				while (parser_is_definitely_type(p, &child_end)) {
					t->token = child_end;
					if (t->token->kind == TOKEN_KW) {
						if (t->token->kw == KW_COMMA) {
							++t->token;
							continue;
						} else if (t->token->kw == KW_RPAREN) {
							/* it *is* a tuple! */
							ret = true;
							++t->token;
							goto end;
						}
					} else break;
				}
			} break;
			case KW_FN: {
				ret = false;
				++t->token;
				if (!token_is_kw(t->token, KW_LPAREN)) {
					break;
				}
				++t->token;
				int paren_level = 1;
				while (t->token->kind != TOKEN_EOF) {
					if (t->token->kind == TOKEN_KW) switch (t->token->kw) {
						case KW_LPAREN:
							++paren_level;
							break;
						case KW_RPAREN:
							--paren_level;
							if (paren_level == 0) {
								++t->token;
								if (token_is_kw(t->token, KW_LBRACE)) goto end; /* void fn expr */
								if (is_decl(t)) /* has return declaration */
									goto end;
								Type return_type;
								bool *enabled = &t->token->where.ctx->enabled;
								bool prev_enabled = *enabled;
							    *enabled = false;
								if (!parse_type(p, &return_type)) {
									/* couldn't parse a return type. void fn type */
									*enabled = prev_enabled;
									ret = true;
									goto end;
								}
							    *enabled = prev_enabled;
								if (token_is_kw(t->token, KW_LBRACE)) {
									/* non-void fn expr */
									goto end;
								}
								/* it's a non-void function type */
								ret = true;
								goto end;
							}
							break;
						default: break;
						}
					++t->token;
				}
			} break;
			case KW_AMPERSAND:
				++t->token; /* continue; see if next thing is definitely a type */
				goto continu;
			default: {
				int x = kw_to_builtin_type(t->token->kw);
			    if ((ret = x != -1)) {
					++t->token;
				}
				break;
			}
			} break;
		case TOKEN_DIRECT:
		case TOKEN_LITERAL_NUM:
		case TOKEN_LITERAL_CHAR:
		case TOKEN_LITERAL_STR:
		case TOKEN_EOF:
		case TOKEN_IDENT:
			ret = false;
			break;
		}
	} while (0);
 end:
	if (ret && end) *end = t->token;
	t->token = start;
	return ret;
}

static bool parse_block(Parser *p, Block *b) {
	b->flags = 0;
	Tokenizer *t = p->tokr;
	Block *prev_block = p->block;
	p->block = b;
	if (!token_is_kw(t->token, KW_LBRACE)) {
		tokr_err(t, "Expected '{' to open block.");
		return false;
	}
	b->start = t->token->where;
	++t->token;	/* move past { */
	b->stmts = NULL;
	bool ret = true;
	b->ret_expr = NULL; /* default to no return unless overwritten later */
	if (!token_is_kw(t->token, KW_RBRACE)) {
		/* non-empty block */
		while (1) {
			Statement *stmt = parser_arr_add(p, &b->stmts);
			bool success = parse_stmt(p, stmt);
			if (!success) {
				ret = false;
			}
			if (token_is_kw(t->token, KW_RBRACE)) {
				break;
			}
			if (t->token->kind == TOKEN_EOF) {
				tokr_err(t, "Expected '}' to close function body.");
				return false;
			}
			
		}
	}
	b->end = t->token->where;
	++t->token;	/* move past } */
	p->block = prev_block;
	return ret;
}

/* does NOT handle empty declaration lists */
static bool parse_decl_list(Parser *p, Declaration **decls, DeclEndKind decl_end) {
	Tokenizer *t = p->tokr;
	bool ret = true;
	bool first = true;
	*decls = NULL;
	while (t->token->kind != TOKEN_EOF &&
		   (first || (
			!token_is_kw(t->token - 1, KW_RPAREN) &&
			!token_is_kw(t->token - 1, KW_LBRACE)))) {
		first = false;
		Declaration *decl = parser_arr_add(p, decls);
		if (!parse_decl(p, decl, decl_end, PARSE_DECL_ALLOW_CONST_WITH_NO_EXPR | PARSE_DECL_ALLOW_SEMI_CONST)) {
			ret = false;
			/* skip to end of list */
			while (t->token->kind != TOKEN_EOF && !ends_decl(t->token, decl_end))
				++t->token;
			break;
		}
	}
	return ret;
}

static bool parse_fn_expr(Parser *p, FnExpr *f) {
	Tokenizer *t = p->tokr;
	f->ret_decls = NULL;
	
	{
		/* help types.c */
		HashTable z = {0};
		f->instances = z;
	}
	/* only called when token is fn */
	assert(token_is_kw(t->token, KW_FN));
	++t->token;
	if (!token_is_kw(t->token, KW_LPAREN)) {
		tokr_err(t, "Expected '(' after 'fn'.");
		return false;
	}
	++t->token;
	f->params = NULL;
	bool ret = true;
	if (token_is_kw(t->token, KW_RPAREN)) {
		++t->token;
	} else {
		if (!parse_decl_list(p, &f->params, DECL_END_RPAREN_COMMA))
		    return false;
		arr_foreach(f->params, Declaration, param)
			param->flags |= DECL_IS_PARAM;
	}
	
	if (t->token->kind == TOKEN_EOF) {
		tokr_err(t, "End of file encountered while parsing parameter list.");
		return false;
	}
	
	if (token_is_kw(t->token, KW_LBRACE)) {
		/* void function */
		f->ret_type.kind = TYPE_VOID;
		f->ret_type.flags = 0;
	} else if (is_decl(t)) {
		if (!parse_decl_list(p, &f->ret_decls, DECL_END_LBRACE_COMMA))
			return false;
		arr_foreach(f->ret_decls, Declaration, d) {
			if ((d->flags & DECL_IS_CONST) || (d->flags & DECL_SEMI_CONST)) {
				err_print(d->where, "Named return values cannot be constant.");
				return false;
			}
		}
		--t->token;	/* move back to { */
		/* just set return type to void. the actual return type will be set by types.c:type_of_fn */
		f->ret_type.kind = TYPE_VOID;
		f->ret_type.flags = 0;
	} else {
		if (!parse_type(p, &f->ret_type)) {
			ret = false;
		}
	}
	if (!parse_block(p, &f->body))
		ret = false;
	f->body.flags |= BLOCK_IS_FN;
	return ret;
}

static void fprint_expr(FILE *out, Expression *e);


#define NOT_AN_OP -1
/* cast/new aren't really operators since they operate on types, not exprs. */
#define CAST_PRECEDENCE 45
#define NEW_PRECEDENCE 22
static int op_precedence(Keyword op) {
	switch (op) {
	case KW_EQ:
	case KW_PLUS_EQ:
	case KW_MINUS_EQ:
	case KW_ASTERISK_EQ:
	case KW_SLASH_EQ:
		return 0;
	case KW_COMMA: return 1;
	case KW_LT: return 3;
	case KW_GT: return 3;
	case KW_LE: return 3;
	case KW_GE: return 3;
	case KW_EQ_EQ: return 3;
	case KW_NE: return 3; 
	case KW_PLUS: return 10;
	case KW_MINUS: return 20;
	case KW_AMPERSAND: return 25;
	case KW_ASTERISK: return 30;
	case KW_SLASH: return 40;
	case KW_EXCLAMATION: return 50;
	case KW_DEL: return 1000;
	default: return NOT_AN_OP;
	}
}

static bool parse_expr(Parser *p, Expression *e, Token *end) {
	Tokenizer *t = p->tokr;
	e->flags = 0;
	e->type.flags = 0;
	if (end == NULL) return false;
	e->where = t->token->where;
	if (end <= t->token) {
		tokr_err(t, "Empty expression.");
		return false;
	}
	Token *before = t->token;
	if (parser_is_definitely_type(p, NULL)) {
		/* it's a type! */
		e->kind = EXPR_TYPE;
		if (!parse_type(p, &e->typeval))
			return false;
		if (t->token == end) return true;
		/* there's more stuff after. maybe it's, e.g. int, float */
	}
	t->token = before;
    
	if (end - t->token == 1) {
		/* 1-token expression */
		switch (t->token->kind) {
		case TOKEN_LITERAL_NUM: {
			NumLiteral *num = &t->token->num;
			switch (num->kind) {
			case NUM_LITERAL_FLOAT:
				e->kind = EXPR_LITERAL_FLOAT;
				e->floatl = num->floatval;
				break;
			case NUM_LITERAL_INT:
				e->kind = EXPR_LITERAL_INT;
				e->intl = num->intval;
				break;
			}
		} break;
		case TOKEN_IDENT:
			e->kind = EXPR_IDENT;
			e->ident = t->token->ident;
			break;
		case TOKEN_LITERAL_STR:
			e->kind = EXPR_LITERAL_STR;
			e->strl = t->token->str;
	    	break;
		case TOKEN_LITERAL_CHAR:
			e->kind = EXPR_LITERAL_CHAR;
			e->charl = t->token->chr;
			break;
		case TOKEN_KW:
			switch (t->token->kw) {
			case KW_TRUE:
				e->kind = EXPR_LITERAL_BOOL;
				e->booll = true;
				break;
			case KW_FALSE:
				e->kind = EXPR_LITERAL_BOOL;
				e->booll = false;
				break;
			default: goto unrecognized;
			}
			break;
		default:
		unrecognized:
			tokr_err(t, "Unrecognized expression.");
			t->token = end + 1;
			return false;
		}
		t->token = end;
		return true;
	}


	Token *start = t->token;
	/* TODO: consider moving this after ops, so that "if true { 5 } else { 3 } as f32" is possible */
	if (t->token->kind == TOKEN_KW) switch (t->token->kw) {
		case KW_FN: {
			/* this is a function */
			e->kind = EXPR_FN;
			if (!parse_fn_expr(p, &e->fn))
				return false;
			
			if (t->token != end) {
				if (token_is_kw(t->token, KW_LPAREN))
					tokr_err(t, "Direct function calling in an expression is not supported.\nYou can wrap the function in parentheses.");
				else
					tokr_err(t, "Expected end of function (did you forget a semicolon?).");
				return false;
			}
			return true;
		}
		case KW_IF: {
			IfExpr *i = &e->if_;
			e->kind = EXPR_IF;
			++t->token;
			Token *cond_end = expr_find_end(p, EXPR_CAN_END_WITH_LBRACE);
			if (!cond_end) return false;
			if (!token_is_kw(cond_end, KW_LBRACE)) {
				t->token = cond_end;
				tokr_err(t, "Expected { to open if body.");
				return false;
			}
			i->cond = parser_new_expr(p);
			if (!parse_expr(p, i->cond, cond_end)) return false;
			if (!parse_block(p, &i->body)) return false;
			IfExpr *curr = i;
			while (1) {
				bool is_else = token_is_kw(t->token, KW_ELSE);
				bool is_elif = token_is_kw(t->token, KW_ELIF);
				if (!is_else && !is_elif) {
					curr->next_elif = NULL;
					break;
				}
				if (curr->cond == NULL) {
					tokr_err(t, "You can't have more elif/elses after an else.");
					return false;
				}
				Expression *next = parser_new_expr(p);
				next->flags = 0;
				next->kind = EXPR_IF;
				next->where = t->token->where;
				curr->next_elif = next;
				IfExpr *nexti = &next->if_;
				if (is_else) {
					++t->token;
					nexti->cond = NULL;
					if (!parse_block(p, &nexti->body)) return false;
				} else {
					/* elif */
					++t->token;
					cond_end = expr_find_end(p, EXPR_CAN_END_WITH_LBRACE);
					if (!cond_end) return false;
					if (!token_is_kw(cond_end, KW_LBRACE)) {
						t->token = cond_end;
						tokr_err(t, "Expected { to open elif body.");
						return false;
					}
					Expression *cond = parser_new_expr(p);
					if (!parse_expr(p, cond, cond_end))
						return false;
					nexti->cond = cond;
					if (!parse_block(p, &nexti->body)) return false;
				}
				curr = nexti;
			}
			return true;
		}
		case KW_WHILE: {
			e->kind = EXPR_WHILE;
			WhileExpr *w = &e->while_;
			++t->token;
			if (token_is_kw(t->token, KW_LBRACE)) {
				/* infinite loop */
				w->cond = NULL;
			} else {
				Token *cond_end = expr_find_end(p, EXPR_CAN_END_WITH_LBRACE);
				if (!cond_end) return false;
				if (!token_is_kw(cond_end, KW_LBRACE)) {
					t->token = cond_end;
					tokr_err(t, "Expected { to open while body.");
					return false;
				}
				Expression *cond = parser_new_expr(p);
				w->cond = cond;
				
				if (!parse_expr(p, cond, cond_end))
					return false;
			}
			if (!parse_block(p, &w->body)) return false;
		    return true;
		}
		case KW_EACH: {
			e->kind = EXPR_EACH;
			EachExpr *ea = &e->each;
			ea->flags = 0;
			ea->value = NULL;
			ea->index = NULL;
			++t->token;
			if (token_is_kw(t->token, KW_COLON)
				|| (t->token->kind == TOKEN_IDENT
				 && (token_is_kw(t->token + 1, KW_COLON)
					 || (token_is_kw(t->token + 1, KW_COMMA)
						 && t->token[2].kind == TOKEN_IDENT
						 && token_is_kw(t->token + 3, KW_COLON))))) {
				if (t->token->kind == TOKEN_IDENT) {
					ea->value = t->token->ident;
					if (ident_eq_str(ea->value, "_")) /* ignore value */
						ea->value = NULL;
					++t->token;
					if (token_is_kw(t->token, KW_COMMA)) {
						++t->token;
						if (t->token->kind == TOKEN_IDENT) {
							ea->index = t->token->ident;
							if (ident_eq_str(ea->index, "_")) /* ignore index */
								ea->index = NULL;
							++t->token;
						} else {
							tokr_err(t, "Expected identifier after , in each statement.");
							return false;
						}
					}
				}
				if (token_is_kw(t->token, KW_COLONCOLON)) {
					tokr_err(t, "The variable(s) in a for loop cannot be constant.");
					return false;
				}
				if (!token_is_kw(t->token, KW_COLON)) {
					tokr_err(t, "Expected : following identifiers in for statement.");
					return false;
				}
				++t->token;
				if (!token_is_kw(t->token, KW_EQ)) {
					ea->flags |= EACH_ANNOTATED_TYPE;
					if (!parse_type(p, &ea->type))
						return false;
					if (!token_is_kw(t->token, KW_EQ)) {
						tokr_err(t, "Expected = in for statement.");
						return false;
					}
				}
				++t->token;
			}
			Token *first_end = expr_find_end(p, EXPR_CAN_END_WITH_COMMA|EXPR_CAN_END_WITH_DOTDOT|EXPR_CAN_END_WITH_LBRACE);
			Expression *first = parser_new_expr(p);
			if (!parse_expr(p, first, first_end))
				return false;
			if (token_is_kw(first_end, KW_LBRACE)) {
				ea->of = first;
			} else if (token_is_kw(first_end, KW_DOTDOT) || token_is_kw(first_end, KW_COMMA)) {
				ea->flags |= EACH_IS_RANGE;
				ea->range.from = first;
				if (token_is_kw(first_end, KW_COMMA)) {
					/* step */
					++t->token;
				    ea->range.step = parser_new_expr(p);
					Token *step_end = expr_find_end(p, EXPR_CAN_END_WITH_LBRACE|EXPR_CAN_END_WITH_DOTDOT);
					if (!parse_expr(p, ea->range.step, step_end))
						return false;
					if (!token_is_kw(step_end, KW_DOTDOT)) {
						err_print(step_end->where, "Expected .. to follow step in for statement.");
						return false;
					}
				} else {
					ea->range.step = NULL;
				}
				++t->token; /* move past .. */
				if (token_is_kw(t->token, KW_LBRACE)) {
					ea->range.to = NULL; /* infinite loop! */
				} else {
					ea->range.to = parser_new_expr(p);
					Token *to_end = expr_find_end(p, EXPR_CAN_END_WITH_LBRACE);
					if (!parse_expr(p, ea->range.to, to_end))
						return false;
					if (!token_is_kw(t->token, KW_LBRACE)) {
						tokr_err(t, "Expected { to open body of for statement.");
						return false;
					}
				}
			} else {
				err_print(first_end->where, "Expected { or .. to follow expression in for statement.");
				return false;
			}
			
			if (!parse_block(p, &ea->body))
				return false;
			return true;
		}
		default: break;
		}


	/* NOTE: the . operator is not handled here, but further down, in order to allow some_struct.fn_member() */
	Token *dot = NULL; /* this keeps track of it for later */
	
	/* Find the lowest-precedence operator not in parentheses/braces/square brackets */
	int paren_level = 0;
	int brace_level = 0;
	int square_level = 0;
	int lowest_precedence = NOT_AN_OP;
	/* e.g. (5+3) */
	bool entirely_within_parentheses = token_is_kw(t->token, KW_LPAREN);
	Token *lowest_precedence_op = NULL;
	for (Token *token = t->token; token < end; ++token) {
		if (token->kind == TOKEN_KW) {
			switch (token->kw) {
			case KW_LPAREN:
				++paren_level;
				break;
			case KW_RPAREN:
				--paren_level;
				if (paren_level == 0 && token != end - 1)
					entirely_within_parentheses = false;
				if (paren_level < 0) {
					t->token = token;
					tokr_err(t, "Excessive closing ).");
					t->token = end + 1;
					return false;
				}
				break;
			case KW_LBRACE:
				++brace_level;
				break;
			case KW_RBRACE:
				--brace_level;
				if (brace_level < 0) {
					t->token = token;
					tokr_err(t, "Excessive closing }.");
					return false;
				}
				break;
			case KW_LSQUARE:
				++square_level;
				break;
			case KW_RSQUARE:
				--square_level;
				if (square_level < 0) {
					tokr_err(t, "Excessive closing ].");
					return false;
				}
				break;
			case KW_DOT:
				if (paren_level == 0 && brace_level == 0 && square_level == 0)
					dot = token;
				break;
			default: { /* OPTIM: use individual cases for each op */
				if (paren_level == 0 && brace_level == 0 && square_level == 0) {
					int precedence;
					switch (token->kw) {
					case KW_AS: precedence = CAST_PRECEDENCE; break;
					case KW_NEW: precedence = NEW_PRECEDENCE; break;
					default: precedence = op_precedence(token->kw); break;
					}
					if (precedence == NOT_AN_OP) break; /* nvm it's not an operator */
					if (lowest_precedence == NOT_AN_OP || precedence <= lowest_precedence) {
						lowest_precedence = precedence;
						lowest_precedence_op = token;
					}
				}
			} break;
			}
		}
	}

	if (paren_level > 0) {
		t->token = start;
		tokr_err(t, "Too many opening parentheses (.");
		return false;
	}
	if (brace_level > 0) {
		t->token = start;
		tokr_err(t, "Too many opening braces {.");
		return false;
	}
	if (square_level > 0) {
		t->token = start;
		tokr_err(t, "Too many opening square brackets [.");
		return false;
	}
	
	if (entirely_within_parentheses) {
		++t->token;	/* move past opening ( */
		if (token_is_kw(t->token, KW_RPAREN)) {
			/* ()foo */
			--t->token;
			tokr_err(t, "Stray () (maybe try wrapping the stuff before this in parentheses)");
			return false;
		}
		Token *new_end = end - 1; /* parse to ending ) */
		if (!parse_expr(p, e, new_end))
			return false;
		++t->token;	/* move past closing ) */
		return true;
	}
	
	if (lowest_precedence != NOT_AN_OP) {
		
		/* Check if this is a unary op not a binary one (e.g. +-3 => +(-3), not (+)-(3)). */
		while (lowest_precedence_op != t->token
			   && lowest_precedence_op[-1].kind == TOKEN_KW
			   && op_precedence(lowest_precedence_op[-1].kw) != NOT_AN_OP) {
			--lowest_precedence_op;
		}

		if (lowest_precedence_op == t->token) {
			/* Unary */
			UnaryOp op;
			bool is_unary = true;
			switch (t->token->kw) {
			case KW_PLUS:
				/* unary + is ignored entirely */
				++t->token;
				/* re-parse this expression without + */
				return parse_expr(p, e, end);
			case KW_MINUS:
				op = UNARY_MINUS;
				break;
			case KW_AMPERSAND:
				op = UNARY_ADDRESS;
				break;
			case KW_ASTERISK:
				op = UNARY_DEREF;
				break;
			case KW_EXCLAMATION:
				op = UNARY_NOT;
				break;
			case KW_NEW:
				e->kind = EXPR_NEW;
				++t->token;
				if (!token_is_kw(t->token, KW_LPAREN)) {
					err_print(t->token->where, "Expected ( to follow new.");
				}
				++t->token;
				if (!parse_type(p, &e->new.type)) return false;
				if (token_is_kw(t->token, KW_COMMA)) {
					/* new(int, 5) */
					++t->token;
					Token *n_end = expr_find_end(p, 0);
					e->new.n = parser_new_expr(p);
					if (!parse_expr(p, e->new.n, n_end))
						return false;
				} else e->new.n = NULL;
				if (!token_is_kw(t->token, KW_RPAREN)) {
					err_print(t->token->where, "Expected ).");
					return false;
				}
				++t->token;
				if (e->new.type.kind == TYPE_TUPLE) {
					err_print(e->where, "You cannot new a tuple.");
					return false;
				}
				if (t->token == end)
					return true;
				/* otherwise, there's more stuff after the new (e.g. new(int, 5).len)*/
				t->token = start;
				goto not_an_op;
			case KW_DEL:
				if (!token_is_kw(t->token + 1, KW_LPAREN)) {
					/* for the future, when del could be a function */
					err_print(e->where, "Expected ( after del.");
					return false;
				}
				op = UNARY_DEL;
				break;
			default:
				is_unary = false;
				break;
			}
			if (!is_unary) {
				tokr_err(t, "%s is not a unary operator.", keywords[lowest_precedence_op->kw]);
				return false;
			}
			e->unary.op = op;
			e->kind = EXPR_UNARY_OP;
			++t->token;
			Expression *of = parser_new_expr(p);
			e->unary.of = of;
			return parse_expr(p, of, end);
		}

		if (lowest_precedence_op->kw == KW_AS) {
			/* cast */
			Expression *casted = parser_new_expr(p);
			e->kind = EXPR_CAST;
			e->cast.expr = casted;
			if (!parse_expr(p, casted, lowest_precedence_op))
				return false;
			t->token = lowest_precedence_op + 1;
			if (!parse_type(p, &e->cast.type))
				return false;
			if (t->token != end) {
				tokr_err(t, "Cast expression continues after type");
				return false;
			}
			return true;
		}
	
		if (lowest_precedence_op->kw == KW_COMMA) {
			Expression lhs, rhs;
			if (!parse_expr(p, &lhs, lowest_precedence_op)) return false;
			t->token = lowest_precedence_op + 1;
			if (!parse_expr(p, &rhs, end)) return false;
			/* create tuple expr out of lhs, rhs */
			e->kind = EXPR_TUPLE;
			e->tuple = NULL;
			if (lhs.kind == EXPR_TUPLE) {
				e->tuple = lhs.tuple;
			} else {
				*(Expression *)parser_arr_add(p, &e->tuple) = lhs;
			}
			if (rhs.kind == EXPR_TUPLE) {
				arr_foreach(rhs.tuple, Expression, r) {
					*(Expression *)parser_arr_add(p, &e->tuple) = *r;
				}
			} else {
				*(Expression *)parser_arr_add(p, &e->tuple) = rhs;
			}
			return true;
		}
		BinaryOp op;
		switch (lowest_precedence_op->kw) {
		case KW_PLUS:
			op = BINARY_ADD;
			break;
		case KW_MINUS:
			op = BINARY_SUB;
			break;
		case KW_EQ_EQ:
			op = BINARY_EQ;
			break;
		case KW_NE:
			op = BINARY_NE;
			break;
		case KW_LT:
			op = BINARY_LT;
			break;
		case KW_LE:
			op = BINARY_LE;
			break;
		case KW_GT:
			op = BINARY_GT;
			break;
		case KW_GE:
			op = BINARY_GE;
			break;
		case KW_EQ:
			op = BINARY_SET;
			break;
		case KW_PLUS_EQ:
			op = BINARY_SET_ADD;
			break;
		case KW_MINUS_EQ:
			op = BINARY_SET_SUB;
			break;
		case KW_ASTERISK_EQ:
			op = BINARY_SET_MUL;
			break;
		case KW_SLASH_EQ:
			op = BINARY_SET_DIV;
			break;
		case KW_ASTERISK:
			op = BINARY_MUL;
			break;
		case KW_SLASH:
			op = BINARY_DIV;
			break;
		case KW_AMPERSAND:
		case KW_EXCLAMATION:
		case KW_DEL:
			err_print(lowest_precedence_op->where, "Unary operator '%s' being used as a binary operator!", kw_to_str(lowest_precedence_op->kw));
			return false;
		default: assert(0); return false;
		}
		e->binary.op = op;
		e->kind = EXPR_BINARY_OP;
		Expression *lhs = parser_new_expr(p);
		e->binary.lhs = lhs;
		if (!parse_expr(p, lhs, lowest_precedence_op)) {
			return false;
		}
	
		Expression *rhs = parser_new_expr(p);
		t->token = lowest_precedence_op + 1;
		e->binary.rhs = rhs;
		if (!parse_expr(p, rhs, end)) {
			return false;
		}		
		return true;
	} else {
	not_an_op:;
		/* function calls, array accesses, etc. */
		
		/* try a function call or array access */
		Token *token = t->token;
		
		/* currently unnecessary: paren_level = square_level = 0; */
		/* 
		   can't call at start, e.g. in (fn() {})(), it is not the empty function ""
		   being called with fn() {} as an argument
		*/
		if (token_is_kw(t->token, KW_LPAREN)) {
			++paren_level;
			++token;
		}
		/* which opening bracket starts the call/array access */
		Token *opening_bracket = NULL;
		Token *closing_bracket = NULL;
		for (; token < end; ++token) {
			if (token->kind == TOKEN_KW) {
				switch (token->kw) {
				case KW_LPAREN:
					if (square_level == 0 && paren_level == 0 && brace_level == 0
						&& token != t->tokens
						&& token[-1].kind != TOKEN_DIRECT /* don't include directives */
						&& !token_is_kw(&token[-1], KW_DOT)) /* or some_struct.("property") */
						opening_bracket = token; /* maybe this left parenthesis opens the function call */
					++paren_level;
					break;
				case KW_LSQUARE:
					if (square_level == 0 && paren_level == 0 && brace_level == 0)
						opening_bracket = token; /* (array access) */
					++square_level;
					break;
				case KW_RPAREN:
					--paren_level;
					if (opening_bracket && token_is_kw(opening_bracket, KW_LPAREN) && square_level == 0 && paren_level == 0 && brace_level == 0)
						closing_bracket = token;
					break;
				case KW_RSQUARE:
					--square_level;
					if (opening_bracket && token_is_kw(opening_bracket, KW_LSQUARE) && square_level == 0 && paren_level == 0 && brace_level == 0)
						closing_bracket = token;
					break;
				case KW_LBRACE:
					++brace_level;
					break;
				case KW_RBRACE:
					--brace_level;
					break;
				default: break;
				}
				
			} else if (token->kind == TOKEN_EOF) {
				if (paren_level > 0) {
					tokr_err(t, "Unmatched ( parenthesis.");
					return false;
				}
				if (square_level > 0) {
					tokr_err(t, "Unmatched [ square bracket.");
					return false;
				}
				break;
			}
		}
		if (opening_bracket && closing_bracket && closing_bracket + 1 == end /* make sure there's nothing after the closing bracket */) {
			switch (opening_bracket->kw) {
			case KW_LPAREN: {
				/* it's a function call! */
				e->kind = EXPR_CALL;
				e->call.fn = parser_new_expr(p);
				if (!parse_expr(p, e->call.fn, opening_bracket)) { /* parse up to ( as function */
					return false;
				}
				t->token = opening_bracket;
				return parse_args(p, &e->call.args);
			}
			case KW_LSQUARE: {
				Expression *arr = parser_new_expr(p);
				/* it's an array access or slice */
				/* parse array */
				if (!parse_expr(p, arr, opening_bracket)) return false;
				
				t->token = opening_bracket + 1;
				Token *iend = NULL;
				if (token_is_kw(t->token, KW_COLON)) {
					/* slice */
					goto expr_is_slice;
				}
				iend = expr_find_end(p, EXPR_CAN_END_WITH_COLON);
				if (iend->kind != TOKEN_KW) {
					err_print(iend->where, "Expected ] or : after index.");
					return false;
				}
				switch (iend->kw) {
				case KW_RSQUARE:
					/* array access */
					e->kind = EXPR_BINARY_OP;
					e->binary.op = BINARY_AT_INDEX;
					e->binary.lhs = arr;
					e->binary.rhs = parser_new_expr(p);
					if (!parse_expr(p, e->binary.rhs, iend))
						return false;
					break;
				expr_is_slice: 
				case KW_COLON: {
					/* slice */
					SliceExpr *s = &e->slice;
					e->kind = EXPR_SLICE;
					s->of = arr;
					if (iend) {
						s->from = parser_new_expr(p);
						if (!parse_expr(p, s->from, iend))
							return false;
					} else {
						/* e.g. x[:5] */
						s->from = NULL;
					}
					assert(token_is_kw(t->token, KW_COLON));
					++t->token;
					if (token_is_kw(t->token, KW_RSQUARE)) {
						/* e.g. x[5:] */
						s->to = NULL;
					} else {
						s->to = parser_new_expr(p);
						Token *to_end = expr_find_end(p, 0);
						if (!token_is_kw(to_end, KW_RSQUARE)) {
							err_print(iend->where, "Expected ] at end of slice.");
							return false;
						}
						if (!parse_expr(p, s->to, to_end))
							return false;
					}
				} break;
				default:
					err_print(iend->where, "Expected ] or : after index.");
					return false;
				}
				++t->token;	/* move past ] */
			    return true;
			}
			default:
				assert(0);
				return false;
			}
		}

		if (t->token->kind == TOKEN_DIRECT) {
			/* it's a directive */
			Expression *single_arg = NULL; /* points to an expr if this is a directive with one expression argument */
			
			switch (t->token->direct) {
			case DIRECT_C:
				e->kind = EXPR_C;
				single_arg = e->c.code = parser_new_expr(p);
				break;
			case DIRECT_SIZEOF:
				e->kind = EXPR_DSIZEOF;
				single_arg = e->dsizeof.of = parser_new_expr(p);
				break;
			case DIRECT_ALIGNOF:
				e->kind = EXPR_DALIGNOF;
				single_arg = e->dalignof.of = parser_new_expr(p);
				break;
			case DIRECT_COUNT: assert(0); break;
			}
			if (single_arg) {
				++t->token;
				if (!token_is_kw(t->token, KW_LPAREN)) {
					err_print(t->token->where, "Expected ( to follow #%s.", directives[t->token->direct]);
					return false;
				}
				++t->token;
				Token *arg_end = expr_find_end(p, 0);
				if (!token_is_kw(arg_end, KW_RPAREN)) {
					err_print(end->where, "Expected ) at end of #%s directive.", directives[t->token->direct]);
					return false;
				}
				if (!parse_expr(p, single_arg, arg_end))
					return false;
				++t->token;
				return true;
			}
		}

		if (token_is_kw(t->token, KW_LBRACE)) {
			/* it's a block */
			e->kind = EXPR_BLOCK;
			if (!parse_block(p, &e->block)) return false;
			if (t->token != end) {
				tokr_err(t, "Expression continues after end of block."); /* TODO: improve this err message */
				return false;
			}
			return true;
		}

		if (dot) {
			e->kind = EXPR_BINARY_OP;
			e->binary.lhs = parser_new_expr(p);
			e->binary.rhs = parser_new_expr(p);
			e->binary.op = BINARY_DOT;
			if (!parse_expr(p, e->binary.lhs, dot))
				return false;
			t->token = dot + 1;
			if (!parse_expr(p, e->binary.rhs, end))
				return false;
			return true;
		}
		
		tokr_err(t, "Unrecognized expression.");
		return false;
	}
}

static inline bool ends_decl(Token *t, DeclEndKind ends_with) {
	if (t->kind != TOKEN_KW) return false;
	switch (ends_with) {
	case DECL_END_SEMICOLON:
		return t->kw == KW_SEMICOLON;
    case DECL_END_RPAREN_COMMA:
		return t->kw == KW_RPAREN || t->kw == KW_COMMA;
	case DECL_END_LBRACE_COMMA:
		return t->kw == KW_LBRACE || t->kw == KW_COMMA;
	default: assert(0); return false;
	}
}

static bool parse_decl(Parser *p, Declaration *d, DeclEndKind ends_with, U16 flags) {
	d->where = p->tokr->token->where;
    d->idents = NULL;
	Tokenizer *t = p->tokr;
	d->flags = 0;
	
	while (1) {
		Identifier *ident = parser_arr_add(p, &d->idents);
		if (t->token->kind != TOKEN_IDENT) {
			tokr_err(t, "Cannot declare non-identifier (%s).", token_kind_to_str(t->token->kind));
			goto ret_false;
		}
		*ident = t->token->ident;
		++t->token;
		if (token_is_kw(t->token, KW_COMMA)) {
			++t->token;
			continue;
		}
		if (token_is_kw(t->token, KW_COLON)) {
			++t->token;
			break;
		}
		if (token_is_kw(t->token, KW_COLONCOLON)) {
			++t->token;
			if (token_is_kw(t->token, KW_COLON) && (flags & PARSE_DECL_ALLOW_SEMI_CONST)) {
				++t->token;
				d->flags |= DECL_SEMI_CONST;
			} else {
				d->flags |= DECL_IS_CONST;
			}
			break;
		}
		tokr_err(t, "Expected ',' to continue listing variables or ':' / '::' to indicate type.");
	    goto ret_false;
	}
	
	if (token_is_kw(t->token, KW_SEMICOLON) || token_is_kw(t->token, KW_RPAREN)) {
		/* e.g. foo :; */
		tokr_err(t, "Cannot infer type without expression.");
		goto ret_false;
	}

	bool annotates_type = !token_is_kw(t->token, KW_EQ) && !token_is_kw(t->token, KW_COMMA);
	if (annotates_type) {
		d->flags |= DECL_ANNOTATES_TYPE;
		Type type;
		if (!parse_type(p, &type)) {
		    goto ret_false;
		}
		d->type = type;
		if (type.kind == TYPE_TUPLE && arr_len(d->type.tuple) != arr_len(d->idents)) {
			err_print(d->where, "Expected to have %lu things declared in declaration, but got %lu.", (unsigned long)arr_len(d->type.tuple), (unsigned long)arr_len(d->idents));
			goto ret_false;
		}
	}
	const char *end_str = NULL;
	switch (ends_with) {
	case DECL_END_SEMICOLON: end_str = "';'"; break;
	case DECL_END_RPAREN_COMMA: end_str = "')' or ','"; break;
	case DECL_END_LBRACE_COMMA: end_str = "'{' or ','"; break;
	}
			
	if (token_is_kw(t->token, KW_EQ)) {
		++t->token;
		d->flags |= DECL_HAS_EXPR;
		uint16_t expr_flags = 0;
		if (ends_with == DECL_END_RPAREN_COMMA)
			expr_flags |= EXPR_CAN_END_WITH_COMMA;
		if (ends_with == DECL_END_LBRACE_COMMA)
			expr_flags |= EXPR_CAN_END_WITH_LBRACE;
		Token *end = expr_find_end(p, expr_flags);
		if (!end || !ends_decl(end, ends_with)) {
			t->token = end;
			tokr_err(t, "Expected %s at end of declaration.", end_str);
		    goto ret_false;
		}
		if (!parse_expr(p, &d->expr, end)) {
			t->token = end; /* move to ; */
		    goto ret_false;
		}
		if (ends_decl(t->token, ends_with)) {
			++t->token;
		} else {
			tokr_err(t, "Expected %s at end of declaration.", end_str);
		    goto ret_false;
		}
	} else if (ends_decl(t->token, ends_with)) {
		++t->token;
	} else {
		tokr_err(t, "Expected %s or '=' at end of delaration.", end_str);
	    goto ret_false;
	}
	
	if ((d->flags & DECL_IS_CONST) && !(d->flags & DECL_HAS_EXPR) && !(flags & PARSE_DECL_ALLOW_CONST_WITH_NO_EXPR)) {
		--t->token;
		/* disallowed constant without an expression, e.g. x :: int; */
		tokr_err(t, "You must have an expression at the end of this constant declaration.");
	    goto ret_false;
	}

	return true;
	
 ret_false:
	/* move past end of decl */
	tokr_skip_semicolon(t);
	return false;
}

static bool is_decl(Tokenizer *t) {
	Token *token = t->token;
	while (1) {
		if (token->kind != TOKEN_IDENT) return false;
		++token;
		if (token->kind != TOKEN_KW) return false;
		if (token->kw == KW_COLON || token->kw == KW_COLONCOLON)
			return true;
		if (token->kw != KW_COMMA) return false;
		++token;
	}
}

static bool parse_stmt(Parser *p, Statement *s) {
	Tokenizer *t = p->tokr;
	if (t->token->kind == TOKEN_EOF) {
		tokr_err(t, "Expected statement.");
		return false;
	}
	s->where = t->token->where;
	s->flags = 0;
	if (token_is_kw(t->token, KW_RETURN)) {
		s->kind = STMT_RET;
		++t->token;
		s->ret.flags = 0;
		if (token_is_kw(t->token, KW_SEMICOLON)) {
			/* return with no expr */
			++t->token;
			return true;
		}
		s->ret.flags |= RET_HAS_EXPR;
		Token *end = expr_find_end(p, 0);
		if (!end) {
			while (t->token->kind != TOKEN_EOF) ++t->token; /* move to end of file */
			return false;
		}
		if (!token_is_kw(end, KW_SEMICOLON)) {
			err_print(end->where, "Expected ';' at end of return statement.");
			t->token = end->kind == TOKEN_EOF ? end : end + 1;
			return false;
		}
		bool success = parse_expr(p, &s->ret.expr, end);
		t->token = end + 1;
		return success;
		
	}
	if (is_decl(t)) {
		s->kind = STMT_DECL;
		if (!parse_decl(p, &s->decl, DECL_END_SEMICOLON, 0)) {
			return false;
		}
		return true;
	} else {
		s->kind = STMT_EXPR;
		Token *end = expr_find_end(p, 0);
		if (!end) {
			tokr_err(t, "No semicolon found at end of statement.");
			while (t->token->kind != TOKEN_EOF) ++t->token; /* move to end of file */
			return false;
		}
		
	    bool success = parse_expr(p, &s->expr, end);
		
		/* go past end of expr regardless of whether successful or not */
		if (token_is_kw(end, KW_SEMICOLON)) {
			t->token = end + 1;	/* skip ; */
		} else  {
			s->flags |= STMT_EXPR_NO_SEMICOLON;
			t->token = end;
		}
		
		return success;
	}
}

static void parser_create(Parser *p, Tokenizer *t, Allocator *allocr) {
	p->tokr = t;
	p->block = NULL;
	p->allocr = allocr;
}

static bool parse_file(Parser *p, ParsedFile *f) {
	Tokenizer *t = p->tokr;
    f->stmts = NULL;
	bool ret = true;
	while (t->token->kind != TOKEN_EOF) {
		Statement *stmt = parser_arr_add(p, &f->stmts);
		if (!parse_stmt(p, stmt))
			ret = false;
		if (token_is_kw(t->token, KW_RBRACE)) {
			tokr_err(t, "} without a matching {.");
			return false;
		}
	}
	return ret;
}

#define PARSE_PRINT_LOCATION(l) /* fprintf(out, "[l%lu]", (unsigned long)(l).line); */

/* in theory, this shouldn't be global, but these functions are mostly for debugging anyways */
static bool parse_printing_after_types;

static void fprint_expr(FILE *out, Expression *e);
static void fprint_stmt(FILE *out, Statement *s);
static void fprint_decl(FILE *out, Declaration *d);

static void fprint_type(FILE *out, Type *t) {
	PARSE_PRINT_LOCATION(t->where);
	char *s = type_to_str(t);
	fprintf(out, "%s", s);
	free(s);
}


static void fprint_block(FILE *out,  Block *b) {
	fprintf(out, "{\n");
	arr_foreach(b->stmts, Statement, stmt) {
		fprint_stmt(out, stmt);
	}
	fprintf(out, "}");
	if (parse_printing_after_types && b->ret_expr) {
		fprintf(out, " returns ");
		fprint_expr(out, b->ret_expr);
	}
	
}

static void fprint_fn_expr(FILE *out, FnExpr *f) {
	bool anyc = fn_has_any_const_params(f);
	bool prev = parse_printing_after_types;
	if (anyc)
		parse_printing_after_types = false;
	fprintf(out, "fn (");
	arr_foreach(f->params, Declaration, decl) {
		if (decl != f->params)
			fprintf(out, ", ");
		fprint_decl(out, decl);
	}
	fprintf(out, ") ");
	fprint_type(out, &f->ret_type);
	fprintf(out, " ");
	fprint_block(out, &f->body);
	if (anyc)
		parse_printing_after_types = prev;
}

static void fprint_args(FILE *out, Argument *args) {
	fprintf(out, "(");
	arr_foreach(args, Argument, arg) {
		if (arg != args) fprintf(out, ", ");
		if (arg->name) {
			fprint_ident(out, arg->name);
			fprintf(out, " = ");
		}
		fprint_expr(out, &arg->val);
	}
	fprintf(out, ")");
}

static void fprint_arg_exprs(FILE *out, Expression *args) {
	fprintf(out, "(");
	arr_foreach(args, Expression, arg) {
		if (arg != args) fprintf(out, ", ");
		fprint_expr(out, arg);
	}
	fprintf(out, ")");
}

static void fprint_val(FILE *f, Value v, Type *t);

static void fprint_expr(FILE *out, Expression *e) {
	PARSE_PRINT_LOCATION(e->where);
	switch (e->kind) {
	case EXPR_LITERAL_INT:
		fprintf(out, "%lld", (long long)e->intl);
		break;
	case EXPR_LITERAL_FLOAT:
		fprintf(out, "%f", (double)e->floatl);
		break;
	case EXPR_LITERAL_STR:
		fprintf(out, "\"%s\"", e->strl.str);
		break;
	case EXPR_LITERAL_BOOL:
		fprintf(out, "%s", e->booll ? "true" : "false");
		break;
	case EXPR_LITERAL_CHAR:
		fprintf(out, "'%c'", e->charl);
		break;
	case EXPR_IDENT:
		fprint_ident(out, e->ident);
		break;
	case EXPR_BINARY_OP: {
		bool prev = parse_printing_after_types;
		fprintf(out, "(");
		fprint_expr(out, e->binary.lhs);
		fprintf(out, ")%s(", binary_op_to_str(e->binary.op));
		if (e->binary.op == BINARY_DOT) {
			parse_printing_after_types = false; /* don't show types for rhs of . */
		}
		fprint_expr(out, e->binary.rhs);
		if (e->binary.op == BINARY_DOT) {
			parse_printing_after_types = prev;
		}
		fprintf(out, ")");
	} break;
	case EXPR_UNARY_OP:
		fprintf(out, "%s", unary_op_to_str(e->unary.op));
		fprintf(out, "(");
		fprint_expr(out, e->unary.of);
		fprintf(out, ")");
		break;
	case EXPR_FN:
		fprint_fn_expr(out, &e->fn);
		break;
	case EXPR_CAST:
		fprintf(out, "cast(");
		fprint_expr(out, e->cast.expr);
		fprintf(out, ", ");
		fprint_type(out, &e->cast.type);
		fprintf(out, ")");
		break;
	case EXPR_NEW:
		fprintf(out, "new ");
		fprint_type(out, &e->new.type);
		break;
	case EXPR_IF:
		if (e->if_.cond) {
			fprintf(out, "(else)? if ");
			fprint_expr(out, e->if_.cond);
		} else {
			fprintf(out, "else");
		}
		fprint_block(out, &e->if_.body);
		if (e->if_.next_elif)
			fprint_expr(out, e->if_.next_elif);
		break;
	case EXPR_WHILE:
	    fprintf(out, "while ");
		if (e->while_.cond) fprint_expr(out, e->while_.cond);
		fprint_block(out, &e->while_.body);
		break;
	case EXPR_EACH: {
		EachExpr *ea = &e->each;
		fprintf(out, "each ");
		if (ea->index) {
			fprint_ident(out, ea->index);
		} else fprintf(out, "_");
		fprintf(out, ", ");
		if (ea->value) {
			fprint_ident(out, ea->value);
		} else fprintf(out, "_");
		fprintf(out, " :");
		if (ea->flags & EACH_ANNOTATED_TYPE)
			fprint_type(out, &ea->type);
		fprintf(out, "= ");
		if (ea->flags & EACH_IS_RANGE) {
			fprint_expr(out, ea->range.from);
			if (parse_printing_after_types) {
				if (ea->range.stepval) {
					fprintf(out, ",");
					fprint_val(out, *ea->range.stepval, &ea->type);
				}
			} else {
				if (ea->range.step) {
					fprintf(out, ",");
					fprint_expr(out, ea->range.step);
				}
			}
			fprintf(out, "..");
			if (ea->range.to) {
				fprint_expr(out, ea->range.to);
			}
			fprintf(out, " ");
		} else {
			fprint_expr(out, ea->of);
		}
		fprint_block(out, &ea->body);
	} break;
	case EXPR_CALL:
		fprint_expr(out, e->call.fn);
		if (parse_printing_after_types) {
			fprint_arg_exprs(out, e->call.arg_exprs);
		} else {
			fprint_args(out, e->call.args);
		}
		break;
	case EXPR_BLOCK:
		fprint_block(out, &e->block);
		break;
	case EXPR_TUPLE:
		fprintf(out, "(");
		arr_foreach(e->tuple, Expression, x) {
			if (x != e->tuple) fprintf(out, ", ");
			fprint_expr(out, x);
		}
		fprintf(out, ")");
		break;
	case EXPR_C:
		fprintf(out, "#C(");
		fprint_expr(out, e->c.code);
		fprintf(out, ")");
		break;
	case EXPR_DSIZEOF:
		fprintf(out, "#sizeof(");
		fprint_expr(out, e->dsizeof.of);
		fprintf(out, ")");
		break;
	case EXPR_DALIGNOF:
		fprintf(out, "#alignof(");
		fprint_expr(out, e->dalignof.of);
		fprintf(out, ")");
		break;
	case EXPR_SLICE: {
		SliceExpr *s = &e->slice;
		fprint_expr(out, s->of);
		fprintf(out, "[");
		if (s->from) fprint_expr(out, s->from);
		fprintf(out, ":");
		if (s->to) fprint_expr(out, s->to);
		fprintf(out, "]");
	} break;
	case EXPR_TYPE:
		fprint_type(out, &e->typeval);
		break;
	case EXPR_VAL:
		fprint_val(out, e->val, &e->type);
		break;
	}
	if (parse_printing_after_types) {
		fprintf(out, ":");
		fprint_type(out, &e->type);
	}
}


static void fprint_decl(FILE *out, Declaration *d) {
	PARSE_PRINT_LOCATION(d->where);
	arr_foreach(d->idents, Identifier, ident) {
		if (ident != d->idents) fprintf(out, ", ");
		fprint_ident(out, *ident);
	}
	if (d->flags & DECL_IS_CONST) {
		fprintf(out, "::");
	} else if (d->flags & DECL_SEMI_CONST) {
		fprintf(out, ":::");
	} else {
		fprintf(out, ":");
	}
	if ((d->flags & DECL_FOUND_TYPE) || (d->flags & DECL_ANNOTATES_TYPE)) {
		fprint_type(out, &d->type);
	}
	if (d->flags & DECL_HAS_EXPR) {
		fprintf(out, "=");
		fprint_expr(out, &d->expr);
	}
}

static void fprint_stmt(FILE *out, Statement *s) {
	PARSE_PRINT_LOCATION(s->where);
	switch (s->kind) {
	case STMT_DECL:
		fprint_decl(out, &s->decl);
		fprintf(out, ";\n");
		break;
	case STMT_EXPR:
		fprint_expr(out, &s->expr);
		fprintf(out, ";\n");
		break;
	case STMT_RET:
		fprintf(out, "return ");
		if (s->ret.flags & RET_HAS_EXPR)
			fprint_expr(out, &s->ret.expr);
		fprintf(out, ";\n");
		break;
	}
}

static void fprint_parsed_file(FILE *out, ParsedFile *f) {
	arr_foreach(f->stmts, Statement, stmt) {
		fprint_stmt(out, stmt);
	}
}

static int decl_ident_index(Declaration *d, Identifier i) {
	int idx = 0;
	arr_foreach(d->idents, Identifier, j) {
		if (i == *j)
			return idx;
		++idx;
	}
	return -1;
}

static inline Value *decl_val_at_index(Declaration *d, int i) {
	return d->type.kind == TYPE_TUPLE ? &d->val.tuple[i] : &d->val;
}

static inline Type *decl_type_at_index(Declaration *d, int i) {
	return d->type.kind == TYPE_TUPLE ? &d->type.tuple[i] : &d->type;
}


static bool expr_is_definitely_const(Expression *e) {
	switch (e->kind) {
	case EXPR_LITERAL_FLOAT:
	case EXPR_LITERAL_INT:
	case EXPR_LITERAL_CHAR:
	case EXPR_LITERAL_STR:
	case EXPR_LITERAL_BOOL:
	case EXPR_DSIZEOF:
	case EXPR_DALIGNOF:
	case EXPR_TYPE:
	case EXPR_VAL:
		return true;
	case EXPR_IF:
	case EXPR_WHILE:
	case EXPR_C:
	case EXPR_NEW:
	case EXPR_CAST:
	case EXPR_CALL:
	case EXPR_BLOCK:
	case EXPR_TUPLE:
	case EXPR_EACH:
	case EXPR_FN:
		return false;
	case EXPR_UNARY_OP:
		return expr_is_definitely_const(e->unary.of);
	case EXPR_BINARY_OP:
		return expr_is_definitely_const(e->binary.lhs)
			&& expr_is_definitely_const(e->binary.rhs);
	case EXPR_SLICE:
		return expr_is_definitely_const(e->slice.of);
	case EXPR_IDENT: {
		IdentDecl *idecl = ident_decl(e->ident);
		assert(idecl);
		return idecl->kind == IDECL_DECL
			&& (idecl->decl->flags & DECL_IS_CONST);
	}
	}
	assert(0);
	return false;
}