727 lines
24 KiB
Rust
727 lines
24 KiB
Rust
import codemap::span;
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import std::map::{hashmap, str_hash, box_str_hash};
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import dvec::{dvec, extensions};
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import base::*;
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import fold::*;
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import ast_util::respan;
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import ast::{ident, path, ty, blk_, expr, expr_path,
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expr_vec, expr_mac, mac_invoc, node_id, expr_index};
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export add_new_extension;
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fn path_to_ident(pth: @path) -> option<ident> {
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if vec::len(pth.idents) == 1u && vec::len(pth.types) == 0u {
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return some(pth.idents[0u]);
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}
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return none;
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}
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//a vec of binders might be a little big.
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type clause = {params: binders, body: @expr};
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/* logically, an arb_depth should contain only one kind of matchable */
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enum arb_depth<T> { leaf(T), seq(@~[arb_depth<T>], span), }
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enum matchable {
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match_expr(@expr),
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match_path(@path),
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match_ident(ast::spanned<ident>),
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match_ty(@ty),
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match_block(ast::blk),
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match_exact, /* don't bind anything, just verify the AST traversal */
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}
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/* for when given an incompatible bit of AST */
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fn match_error(cx: ext_ctxt, m: matchable, expected: ~str) -> ! {
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match m {
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match_expr(x) => cx.span_fatal(
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x.span, ~"this argument is an expr, expected " + expected),
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match_path(x) => cx.span_fatal(
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x.span, ~"this argument is a path, expected " + expected),
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match_ident(x) => cx.span_fatal(
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x.span, ~"this argument is an ident, expected " + expected),
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match_ty(x) => cx.span_fatal(
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x.span, ~"this argument is a type, expected " + expected),
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match_block(x) => cx.span_fatal(
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x.span, ~"this argument is a block, expected " + expected),
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match_exact => cx.bug(~"what is a match_exact doing in a bindings?")
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}
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}
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// We can't make all the matchables in a match_result the same type because
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// idents can be paths, which can be exprs.
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// If we want better match failure error messages (like in Fortifying Syntax),
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// we'll want to return something indicating amount of progress and location
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// of failure instead of `none`.
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type match_result = option<arb_depth<matchable>>;
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type selector = fn@(matchable) -> match_result;
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fn elts_to_ell(cx: ext_ctxt, elts: ~[@expr]) ->
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{pre: ~[@expr], rep: option<@expr>, post: ~[@expr]} {
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let mut idx: uint = 0u;
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let mut res = none;
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for elts.each |elt| {
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match elt.node {
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expr_mac(m) => match m.node {
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ast::mac_ellipsis => {
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if res != none {
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cx.span_fatal(m.span, ~"only one ellipsis allowed");
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}
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res =
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some({pre: vec::slice(elts, 0u, idx - 1u),
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rep: some(elts[idx - 1u]),
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post: vec::slice(elts, idx + 1u, vec::len(elts))});
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}
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_ => ()
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}
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_ => ()
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}
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idx += 1u;
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}
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return match res {
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some(val) => val,
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none => {pre: elts, rep: none, post: ~[]}
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}
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}
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fn option_flatten_map<T: copy, U: copy>(f: fn@(T) -> option<U>, v: ~[T]) ->
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option<~[U]> {
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let mut res = ~[];
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for v.each |elem| {
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match f(elem) {
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none => return none,
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some(fv) => vec::push(res, fv)
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}
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}
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return some(res);
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}
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fn a_d_map(ad: arb_depth<matchable>, f: selector) -> match_result {
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match ad {
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leaf(x) => return f(x),
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seq(ads, span) => match option_flatten_map(|x| a_d_map(x, f), *ads) {
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none => return none,
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some(ts) => return some(seq(@ts, span))
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}
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}
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}
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fn compose_sels(s1: selector, s2: selector) -> selector {
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fn scomp(s1: selector, s2: selector, m: matchable) -> match_result {
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return match s1(m) {
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none => none,
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some(matches) => a_d_map(matches, s2)
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}
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}
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return { |x| scomp(s1, s2, x) };
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}
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type binders =
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{real_binders: hashmap<ident, selector>,
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literal_ast_matchers: dvec<selector>};
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type bindings = hashmap<ident, arb_depth<matchable>>;
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fn acumm_bindings(_cx: ext_ctxt, _b_dest: bindings, _b_src: bindings) { }
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/* these three functions are the big moving parts */
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/* create the selectors needed to bind and verify the pattern */
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fn pattern_to_selectors(cx: ext_ctxt, e: @expr) -> binders {
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let res: binders =
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{real_binders: box_str_hash::<selector>(),
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literal_ast_matchers: dvec()};
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//this oughta return binders instead, but macro args are a sequence of
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//expressions, rather than a single expression
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fn trivial_selector(m: matchable) -> match_result {
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return some(leaf(m));
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}
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p_t_s_rec(cx, match_expr(e), trivial_selector, res);
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return res;
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}
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/* use the selectors on the actual arguments to the macro to extract
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bindings. Most of the work is done in p_t_s, which generates the
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selectors. */
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fn use_selectors_to_bind(b: binders, e: @expr) -> option<bindings> {
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let res = box_str_hash::<arb_depth<matchable>>();
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//need to do this first, to check vec lengths.
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for b.literal_ast_matchers.each |sel| {
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match sel(match_expr(e)) { none => return none, _ => () }
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}
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let mut never_mind: bool = false;
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for b.real_binders.each |key, val| {
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match val(match_expr(e)) {
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none => never_mind = true,
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some(mtc) => { res.insert(key, mtc); }
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}
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};
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//HACK: `ret` doesn't work in `for each`
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if never_mind { return none; }
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return some(res);
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}
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/* use the bindings on the body to generate the expanded code */
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fn transcribe(cx: ext_ctxt, b: bindings, body: @expr) -> @expr {
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let idx_path: @mut ~[uint] = @mut ~[];
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fn new_id(_old: node_id, cx: ext_ctxt) -> node_id { return cx.next_id(); }
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fn new_span(cx: ext_ctxt, sp: span) -> span {
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/* this discards information in the case of macro-defining macros */
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return {lo: sp.lo, hi: sp.hi, expn_info: cx.backtrace()};
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}
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let afp = default_ast_fold();
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let f_pre =
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@{fold_ident: |x,y|transcribe_ident(cx, b, idx_path, x, y),
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fold_path: |x,y|transcribe_path(cx, b, idx_path, x, y),
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fold_expr: |x,y,z|
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transcribe_expr(cx, b, idx_path, x, y, z, afp.fold_expr)
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,
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fold_ty: |x,y,z|
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transcribe_type(cx, b, idx_path,
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x, y, z, afp.fold_ty)
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,
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fold_block: |x,y,z|
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transcribe_block(cx, b, idx_path, x, y, z, afp.fold_block)
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,
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map_exprs: |x,y|
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transcribe_exprs(cx, b, idx_path, x, y)
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,
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new_id: |x|new_id(x, cx)
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with *afp};
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let f = make_fold(f_pre);
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let result = f.fold_expr(body);
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return result;
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}
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/* helper: descend into a matcher */
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fn follow(m: arb_depth<matchable>, idx_path: @mut ~[uint]) ->
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arb_depth<matchable> {
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let mut res: arb_depth<matchable> = m;
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for vec::each(*idx_path) |idx| {
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res = match res {
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leaf(_) => return res,/* end of the line */
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seq(new_ms, _) => new_ms[idx]
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}
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}
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return res;
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}
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fn follow_for_trans(cx: ext_ctxt, mmaybe: option<arb_depth<matchable>>,
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idx_path: @mut ~[uint]) -> option<matchable> {
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match mmaybe {
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none => return none,
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some(m) => {
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return match follow(m, idx_path) {
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seq(_, sp) => {
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cx.span_fatal(sp,
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~"syntax matched under ... but not " +
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~"used that way.")
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}
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leaf(m) => return some(m)
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}
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}
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}
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}
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/* helper for transcribe_exprs: what vars from `b` occur in `e`? */
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fn free_vars(b: bindings, e: @expr, it: fn(ident)) {
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let idents: hashmap<ident, ()> = box_str_hash::<()>();
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fn mark_ident(&&i: ident, _fld: ast_fold, b: bindings,
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idents: hashmap<ident, ()>) -> ident {
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if b.contains_key(i) { idents.insert(i, ()); }
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return i;
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}
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// using fold is a hack: we want visit, but it doesn't hit idents ) :
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// solve this with macros
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let f_pre =
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@{fold_ident: |x,y|mark_ident(x, y, b, idents)
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with *default_ast_fold()};
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let f = make_fold(f_pre);
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f.fold_expr(e); // ignore result
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for idents.each_key |x| { it(x); };
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}
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/* handle sequences (anywhere in the AST) of exprs, either real or ...ed */
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fn transcribe_exprs(cx: ext_ctxt, b: bindings, idx_path: @mut ~[uint],
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recur: fn@(&&@expr) -> @expr,
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exprs: ~[@expr]) -> ~[@expr] {
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match elts_to_ell(cx, exprs) {
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{pre: pre, rep: repeat_me_maybe, post: post} => {
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let mut res = vec::map(pre, recur);
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match repeat_me_maybe {
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none => (),
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some(repeat_me) => {
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let mut repeat: option<{rep_count: uint, name: ident}> = none;
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/* we need to walk over all the free vars in lockstep, except for
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the leaves, which are just duplicated */
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do free_vars(b, repeat_me) |fv| {
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let cur_pos = follow(b.get(fv), idx_path);
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match cur_pos {
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leaf(_) => (),
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seq(ms, _) => {
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match repeat {
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none => {
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repeat = some({rep_count: vec::len(*ms), name: fv});
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}
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some({rep_count: old_len, name: old_name}) => {
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let len = vec::len(*ms);
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if old_len != len {
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let msg =
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fmt!{"'%s' occurs %u times, but ", *fv, len} +
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fmt!{"'%s' occurs %u times", *old_name,
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old_len};
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cx.span_fatal(repeat_me.span, msg);
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}
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}
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}
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}
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}
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};
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match repeat {
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none => {
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cx.span_fatal(repeat_me.span,
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~"'...' surrounds an expression without any" +
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~" repeating syntax variables");
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}
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some({rep_count: rc, _}) => {
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/* Whew, we now know how how many times to repeat */
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let mut idx: uint = 0u;
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while idx < rc {
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vec::push(*idx_path, idx);
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vec::push(res, recur(repeat_me)); // whew!
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vec::pop(*idx_path);
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idx += 1u;
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}
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}
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}
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}
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}
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res = vec::append(res, vec::map(post, recur));
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return res;
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}
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}
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}
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// substitute, in a position that's required to be an ident
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fn transcribe_ident(cx: ext_ctxt, b: bindings, idx_path: @mut ~[uint],
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&&i: ident, _fld: ast_fold) -> ident {
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return match follow_for_trans(cx, b.find(i), idx_path) {
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some(match_ident(a_id)) => a_id.node,
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some(m) => match_error(cx, m, ~"an identifier"),
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none => i
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}
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}
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fn transcribe_path(cx: ext_ctxt, b: bindings, idx_path: @mut ~[uint],
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p: path, _fld: ast_fold) -> path {
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// Don't substitute into qualified names.
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if vec::len(p.types) > 0u || vec::len(p.idents) != 1u { return p; }
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match follow_for_trans(cx, b.find(p.idents[0]), idx_path) {
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some(match_ident(id)) => {
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{span: id.span, global: false, idents: ~[id.node],
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rp: none, types: ~[]}
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}
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some(match_path(a_pth)) => *a_pth,
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some(m) => match_error(cx, m, ~"a path"),
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none => p
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}
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}
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fn transcribe_expr(cx: ext_ctxt, b: bindings, idx_path: @mut ~[uint],
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e: ast::expr_, s: span, fld: ast_fold,
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orig: fn@(ast::expr_, span, ast_fold)->(ast::expr_, span))
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-> (ast::expr_, span)
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{
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return match e {
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expr_path(p) => {
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// Don't substitute into qualified names.
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if vec::len(p.types) > 0u || vec::len(p.idents) != 1u {
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(e, s);
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}
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match follow_for_trans(cx, b.find(p.idents[0]), idx_path) {
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some(match_ident(id)) => {
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(expr_path(@{span: id.span,
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global: false,
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idents: ~[id.node],
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rp: none,
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types: ~[]}), id.span)
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}
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some(match_path(a_pth)) => (expr_path(a_pth), s),
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some(match_expr(a_exp)) => (a_exp.node, a_exp.span),
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some(m) => match_error(cx, m, ~"an expression"),
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none => orig(e, s, fld)
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}
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}
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_ => orig(e, s, fld)
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}
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}
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fn transcribe_type(cx: ext_ctxt, b: bindings, idx_path: @mut ~[uint],
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t: ast::ty_, s: span, fld: ast_fold,
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orig: fn@(ast::ty_, span, ast_fold) -> (ast::ty_, span))
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-> (ast::ty_, span)
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{
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return match t {
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ast::ty_path(pth, _) => {
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match path_to_ident(pth) {
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some(id) => {
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match follow_for_trans(cx, b.find(id), idx_path) {
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some(match_ty(ty)) => (ty.node, ty.span),
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some(m) => match_error(cx, m, ~"a type"),
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none => orig(t, s, fld)
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}
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}
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none => orig(t, s, fld)
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}
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}
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_ => orig(t, s, fld)
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}
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}
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/* for parsing reasons, syntax variables bound to blocks must be used like
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`{v}` */
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fn transcribe_block(cx: ext_ctxt, b: bindings, idx_path: @mut ~[uint],
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blk: blk_, s: span, fld: ast_fold,
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orig: fn@(blk_, span, ast_fold) -> (blk_, span))
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-> (blk_, span)
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{
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return match block_to_ident(blk) {
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some(id) => {
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match follow_for_trans(cx, b.find(id), idx_path) {
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some(match_block(new_blk)) => (new_blk.node, new_blk.span),
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// possibly allow promotion of ident/path/expr to blocks?
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some(m) => match_error(cx, m, ~"a block"),
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none => orig(blk, s, fld)
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}
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}
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none => orig(blk, s, fld)
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}
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}
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/* traverse the pattern, building instructions on how to bind the actual
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argument. ps accumulates instructions on navigating the tree.*/
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fn p_t_s_rec(cx: ext_ctxt, m: matchable, s: selector, b: binders) {
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//it might be possible to traverse only exprs, not matchables
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match m {
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match_expr(e) => {
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match e.node {
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expr_path(p_pth) => p_t_s_r_path(cx, p_pth, s, b),
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expr_vec(p_elts, _) => {
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match elts_to_ell(cx, p_elts) {
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{pre: pre, rep: some(repeat_me), post: post} => {
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p_t_s_r_length(cx, vec::len(pre) + vec::len(post), true, s,
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b);
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if vec::len(pre) > 0u {
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p_t_s_r_actual_vector(cx, pre, true, s, b);
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}
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p_t_s_r_ellipses(cx, repeat_me, vec::len(pre), s, b);
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if vec::len(post) > 0u {
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cx.span_unimpl(e.span,
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~"matching after `...` not yet supported");
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}
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}
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{pre: pre, rep: none, post: post} => {
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if post != ~[] {
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cx.bug(~"elts_to_ell provided an invalid result");
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}
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p_t_s_r_length(cx, vec::len(pre), false, s, b);
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p_t_s_r_actual_vector(cx, pre, false, s, b);
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}
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}
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}
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/* FIXME (#2251): handle embedded types and blocks, at least */
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expr_mac(mac) => {
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p_t_s_r_mac(cx, mac, s, b);
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}
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_ => {
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fn select(cx: ext_ctxt, m: matchable, pat: @expr) ->
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match_result {
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return match m {
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match_expr(e) => {
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if e == pat { some(leaf(match_exact)) } else { none }
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}
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_ => cx.bug(~"broken traversal in p_t_s_r")
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}
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}
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b.literal_ast_matchers.push(|x| select(cx, x, e));
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}
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}
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}
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_ => cx.bug(~"undocumented invariant in p_t_s_rec")
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}
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}
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/* make a match more precise */
|
|
fn specialize_match(m: matchable) -> matchable {
|
|
return match m {
|
|
match_expr(e) => {
|
|
match e.node {
|
|
expr_path(pth) => {
|
|
match path_to_ident(pth) {
|
|
some(id) => match_ident(respan(pth.span, id)),
|
|
none => match_path(pth)
|
|
}
|
|
}
|
|
_ => m
|
|
}
|
|
}
|
|
_ => m
|
|
}
|
|
}
|
|
|
|
/* pattern_to_selectors helper functions */
|
|
fn p_t_s_r_path(cx: ext_ctxt, p: @path, s: selector, b: binders) {
|
|
match path_to_ident(p) {
|
|
some(p_id) => {
|
|
fn select(cx: ext_ctxt, m: matchable) -> match_result {
|
|
return match m {
|
|
match_expr(e) => some(leaf(specialize_match(m))),
|
|
_ => cx.bug(~"broken traversal in p_t_s_r")
|
|
}
|
|
}
|
|
if b.real_binders.contains_key(p_id) {
|
|
cx.span_fatal(p.span, ~"duplicate binding identifier");
|
|
}
|
|
b.real_binders.insert(p_id, compose_sels(s, |x| select(cx, x)));
|
|
}
|
|
none => ()
|
|
}
|
|
}
|
|
|
|
fn block_to_ident(blk: blk_) -> option<ident> {
|
|
if vec::len(blk.stmts) != 0u { return none; }
|
|
return match blk.expr {
|
|
some(expr) => match expr.node {
|
|
expr_path(pth) => path_to_ident(pth),
|
|
_ => none
|
|
}
|
|
none => none
|
|
}
|
|
}
|
|
|
|
fn p_t_s_r_mac(cx: ext_ctxt, mac: ast::mac, _s: selector, _b: binders) {
|
|
fn select_pt_1(cx: ext_ctxt, m: matchable,
|
|
fn_m: fn(ast::mac) -> match_result) -> match_result {
|
|
return match m {
|
|
match_expr(e) => match e.node {
|
|
expr_mac(mac) => fn_m(mac),
|
|
_ => none
|
|
}
|
|
_ => cx.bug(~"broken traversal in p_t_s_r")
|
|
}
|
|
}
|
|
fn no_des(cx: ext_ctxt, sp: span, syn: ~str) -> ! {
|
|
cx.span_fatal(sp, ~"destructuring " + syn + ~" is not yet supported");
|
|
}
|
|
match mac.node {
|
|
ast::mac_ellipsis => cx.span_fatal(mac.span, ~"misused `...`"),
|
|
ast::mac_invoc(_, _, _) => no_des(cx, mac.span, ~"macro calls"),
|
|
ast::mac_invoc_tt(_, _) => no_des(cx, mac.span, ~"macro calls"),
|
|
ast::mac_aq(_,_) => no_des(cx, mac.span, ~"antiquotes"),
|
|
ast::mac_var(_) => no_des(cx, mac.span, ~"antiquote variables")
|
|
}
|
|
}
|
|
|
|
fn p_t_s_r_ellipses(cx: ext_ctxt, repeat_me: @expr, offset: uint, s: selector,
|
|
b: binders) {
|
|
fn select(cx: ext_ctxt, repeat_me: @expr, offset: uint, m: matchable) ->
|
|
match_result {
|
|
return match m {
|
|
match_expr(e) => {
|
|
match e.node {
|
|
expr_vec(arg_elts, _) => {
|
|
let mut elts = ~[];
|
|
let mut idx = offset;
|
|
while idx < vec::len(arg_elts) {
|
|
vec::push(elts, leaf(match_expr(arg_elts[idx])));
|
|
idx += 1u;
|
|
}
|
|
|
|
// using repeat_me.span is a little wacky, but the
|
|
// error we want to report is one in the macro def
|
|
some(seq(@elts, repeat_me.span))
|
|
}
|
|
_ => none
|
|
}
|
|
}
|
|
_ => cx.bug(~"broken traversal in p_t_s_r")
|
|
}
|
|
}
|
|
p_t_s_rec(cx, match_expr(repeat_me),
|
|
compose_sels(s, |x| select(cx, repeat_me, offset, x)), b);
|
|
}
|
|
|
|
|
|
fn p_t_s_r_length(cx: ext_ctxt, len: uint, at_least: bool, s: selector,
|
|
b: binders) {
|
|
fn len_select(_cx: ext_ctxt, m: matchable, at_least: bool, len: uint) ->
|
|
match_result {
|
|
return match m {
|
|
match_expr(e) => {
|
|
match e.node {
|
|
expr_vec(arg_elts, _) => {
|
|
let actual_len = vec::len(arg_elts);
|
|
if at_least && actual_len >= len || actual_len == len {
|
|
some(leaf(match_exact))
|
|
} else { none }
|
|
}
|
|
_ => none
|
|
}
|
|
}
|
|
_ => none
|
|
}
|
|
}
|
|
b.literal_ast_matchers.push(
|
|
compose_sels(s, |x| len_select(cx, x, at_least, len)));
|
|
}
|
|
|
|
fn p_t_s_r_actual_vector(cx: ext_ctxt, elts: ~[@expr], _repeat_after: bool,
|
|
s: selector, b: binders) {
|
|
let mut idx: uint = 0u;
|
|
while idx < vec::len(elts) {
|
|
fn select(cx: ext_ctxt, m: matchable, idx: uint) -> match_result {
|
|
return match m {
|
|
match_expr(e) => {
|
|
match e.node {
|
|
expr_vec(arg_elts, _) => {
|
|
some(leaf(match_expr(arg_elts[idx])))
|
|
}
|
|
_ => none
|
|
}
|
|
}
|
|
_ => cx.bug(~"broken traversal in p_t_s_r")
|
|
}
|
|
}
|
|
p_t_s_rec(cx, match_expr(elts[idx]),
|
|
compose_sels(s, |x, copy idx| select(cx, x, idx)), b);
|
|
idx += 1u;
|
|
}
|
|
}
|
|
|
|
fn add_new_extension(cx: ext_ctxt, sp: span, arg: ast::mac_arg,
|
|
_body: ast::mac_body) -> base::macro_def {
|
|
let args = get_mac_args_no_max(cx, sp, arg, 0u, ~"macro");
|
|
|
|
let mut macro_name: option<@~str> = none;
|
|
let mut clauses: ~[@clause] = ~[];
|
|
for args.each |arg| {
|
|
match arg.node {
|
|
expr_vec(elts, mutbl) => {
|
|
if vec::len(elts) != 2u {
|
|
cx.span_fatal((*arg).span,
|
|
~"extension clause must consist of ~[" +
|
|
~"macro invocation, expansion body]");
|
|
}
|
|
|
|
|
|
match elts[0u].node {
|
|
expr_mac(mac) => {
|
|
match mac.node {
|
|
mac_invoc(pth, invoc_arg, body) => {
|
|
match path_to_ident(pth) {
|
|
some(id) => match macro_name {
|
|
none => macro_name = some(id),
|
|
some(other_id) => if id != other_id {
|
|
cx.span_fatal(pth.span,
|
|
~"macro name must be " +
|
|
~"consistent");
|
|
}
|
|
}
|
|
none => cx.span_fatal(pth.span,
|
|
~"macro name must not be a path")
|
|
}
|
|
let arg = match invoc_arg {
|
|
some(arg) => arg,
|
|
none => cx.span_fatal(mac.span,
|
|
~"macro must have arguments")
|
|
};
|
|
vec::push(clauses,
|
|
@{params: pattern_to_selectors(cx, arg),
|
|
body: elts[1u]});
|
|
|
|
// FIXME (#2251): check duplicates (or just simplify
|
|
// the macro arg situation)
|
|
}
|
|
_ => {
|
|
cx.span_bug(mac.span, ~"undocumented invariant in \
|
|
add_extension");
|
|
}
|
|
}
|
|
}
|
|
_ => {
|
|
cx.span_fatal(elts[0u].span,
|
|
~"extension clause must" +
|
|
~" start with a macro invocation.");
|
|
}
|
|
}
|
|
}
|
|
_ => {
|
|
cx.span_fatal((*arg).span,
|
|
~"extension must be ~[clause, " + ~" ...]");
|
|
}
|
|
}
|
|
}
|
|
|
|
let ext = |a,b,c,d, move clauses| generic_extension(a,b,c,d,clauses);
|
|
|
|
return {ident:
|
|
match macro_name {
|
|
some(id) => id,
|
|
none => cx.span_fatal(sp, ~"macro definition must have " +
|
|
~"at least one clause")
|
|
},
|
|
ext: normal({expander: ext, span: some(option::get(arg).span)})};
|
|
|
|
fn generic_extension(cx: ext_ctxt, sp: span, arg: ast::mac_arg,
|
|
_body: ast::mac_body,
|
|
clauses: ~[@clause]) -> @expr {
|
|
let arg = match arg {
|
|
some(arg) => arg,
|
|
none => cx.span_fatal(sp, ~"macro must have arguments")
|
|
};
|
|
for clauses.each |c| {
|
|
match use_selectors_to_bind(c.params, arg) {
|
|
some(bindings) => return transcribe(cx, bindings, c.body),
|
|
none => again
|
|
}
|
|
}
|
|
cx.span_fatal(sp, ~"no clauses match macro invocation");
|
|
}
|
|
}
|
|
|
|
|
|
|
|
//
|
|
// Local Variables:
|
|
// mode: rust
|
|
// fill-column: 78;
|
|
// indent-tabs-mode: nil
|
|
// c-basic-offset: 4
|
|
// buffer-file-coding-system: utf-8-unix
|
|
// End:
|
|
//
|