ww/lib/ww/parse/decl.ww

// lib/ww/parse/decl.ww — declaration parsing, split out of parse.ww.

use os;
use mem;
use tok;

fn parseuse(p: *parser) *node = {
	let pf: str = p.curfile;
	let pl: i32 = p.curline;
	let pc: i32 = p.curcol;
	advance(p);	// past `use`
	let n: *node = newnode(p.a, nkind.N_USE, pf, pl, pc);
	let id: str;
	expectident(p, &id);
	n.str = id;
	expecttok(p, tkind.TK_SEMI, "expected ';' after use");
	return n;
};

fn parsedef(p: *parser, exported: i32) *node = {
	let pf: str = p.curfile;
	let pl: i32 = p.curline;
	let pc: i32 = p.curcol;
	advance(p);	// past `def`
	let n: *node = newnode(p.a, nkind.N_DEF, pf, pl, pc);
	n.module = p.l.module;
	let id: str;
	expectident(p, &id);
	n.str = id;
	expecttok(p, tkind.TK_COLON, "expected ':' in def");
	n.lhs = parsetype(p);
	expecttok(p, tkind.TK_ASSIGN, "expected '=' in def");
	n.rhs = parseexpr(p);
	expecttok(p, tkind.TK_SEMI, "expected ';' after def");
	n.exported = exported;
	return n;
};

fn parselet(p: *parser, exported: i32) *node = {
	let pf: str = p.curfile;
	let pl: i32 = p.curline;
	let pc: i32 = p.curcol;
	// Accept `let` or `const`. Const-bound bindings are marked via
	// n.op = tkind.TK_CONST so the checker can reject reassignment.
	let is_const: i32 = 0;
	if (p.curkind == tkind.TK_CONST) { is_const = 1; };
	advance(p);
	let n: *node = newnode(p.a, nkind.N_LET, pf, pl, pc);
	n.module = p.l.module;
	let id: str;
	expectbindname(p, &id);
	n.str = id;
	if (accepttok(p, tkind.TK_COLON)) {
		n.lhs = parsetype(p);
	};
	if (accepttok(p, tkind.TK_ASSIGN)) {
		n.rhs = parseexpr(p);
	};
	expecttok(p, tkind.TK_SEMI, "expected ';' after let");
	n.exported = exported;
	if (is_const != 0) { n.op = tkind.TK_CONST; };
	return n;
};

fn parseattrs(p: *parser) *node = {
	let head: *node = nil;
	let tail: *node = nil;
	for (p.curkind == tkind.TK_AT) {
		let pf: str = p.curfile;
		let pl: i32 = p.curline;
		let pc: i32 = p.curcol;
		advance(p);
		let a: *node = newnode(p.a, nkind.N_ATTR, pf, pl, pc);
		let id: str;
		expectident(p, &id);
		a.str = id;
		// `@name(args...)` for FFI-style attrs; `@name` for marker-
		// only attrs like @test (no parens).
		if (accepttok(p, tkind.TK_LPAREN)) {
			let arghead: *node = nil;
			parsearglist(p, tkind.TK_RPAREN, &arghead);
			a.list = arghead;
			expecttok(p, tkind.TK_RPAREN, "expected ')' after attribute args");
		};
		if (head == nil) { head = a; tail = a; }
		else { tail.next = a; tail = a; };
	};
	return head;
};

fn parseparams(p: *parser) *node = {
	if (p.curkind == tkind.TK_RPAREN) { return nil; };
	let head: *node = nil;
	let tail: *node = nil;
	for (true) {
		let pf: str = p.curfile;
		let pl: i32 = p.curline;
		let pc: i32 = p.curcol;
		let n: *node = newnode(p.a, nkind.N_PARAM, pf, pl, pc);
		// Param form: (IDENT|'_') ':' type. Anonymous-type-only params
		// (used in fn type expressions) aren't yet wired here.
		let id: str;
		expectbindname(p, &id);
		n.str = id;
		expecttok(p, tkind.TK_COLON, "expected ':' in parameter");
		n.lhs = parsetype(p);
		if (head == nil) { head = n; tail = n; }
		else { tail.next = n; tail = n; };
		if (!accepttok(p, tkind.TK_COMMA)) { break; };
		if (p.curkind == tkind.TK_RPAREN) { break; };
	};
	return head;
};

fn parsefn(p: *parser, exported: i32, attrs: *node) *node = {
	let pf: str = p.curfile;
	let pl: i32 = p.curline;
	let pc: i32 = p.curcol;
	advance(p);	// past `fn`
	let n: *node = newnode(p.a, nkind.N_FNDECL, pf, pl, pc);
	n.module = p.l.module;
	let id: str;
	expectident(p, &id);
	n.str = id;
	expecttok(p, tkind.TK_LPAREN, "expected '(' after fn name");
	n.list = parseparams(p);
	expecttok(p, tkind.TK_RPAREN, "expected ')' after params");
	if (p.curkind != tkind.TK_ASSIGN) {
		if (p.curkind != tkind.TK_SEMI) {
			n.lhs = parsetype(p);
		};
	};
	if (accepttok(p, tkind.TK_ASSIGN)) {
		n.body = parseblock(p);
		expecttok(p, tkind.TK_SEMI, "expected ';' after fn body");
	} else {
		// Body-less fn: FFI declaration (`fn name(args) ret;`).
		expecttok(p, tkind.TK_SEMI, "expected ';' after fn header");
	};
	n.exported = exported;
	n.attr = attrs;
	return n;
};

fn parsetypedecl(p: *parser, exported: i32) *node = {
	let pf: str = p.curfile;
	let pl: i32 = p.curline;
	let pc: i32 = p.curcol;
	advance(p);	// past `type`
	let n: *node = newnode(p.a, nkind.N_TYPEDECL, pf, pl, pc);
	n.module = p.l.module;
	let id: str;
	expectident(p, &id);
	n.str = id;
	expecttok(p, tkind.TK_ASSIGN, "expected '=' in type decl");
	n.lhs = parsetype(p);
	expecttok(p, tkind.TK_SEMI, "expected ';' after type decl");
	n.exported = exported;
	return n;
};