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Allow [a, b, ..., c] transcription patterns in MBE.
This commit is contained in:
Paul Stansifer
parent
d2f9b15052
commit
87b56b5565
@ -92,19 +92,21 @@ type match_result = option::t[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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-> {fixed: [@expr], rep: option::t[@expr]} {
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-> {pre: [@expr], rep: option::t[@expr], post: [@expr]} {
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let idx: uint = 0u;
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let res = none;
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for elt: @expr in elts {
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alt elt.node {
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expr_mac(m) {
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alt m.node {
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ast::mac_ellipsis. {
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let last = ivec::len(elts) - 1u;
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if idx != last {
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cx.span_fatal(m.span, "ellipses must occur last");
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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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ret {fixed: ivec::slice(elts, 0u, last - 1u),
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rep: some(elts.(last - 1u))};
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res = some({pre: ivec::slice(elts, 0u, idx - 1u),
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rep: some(elts.(idx - 1u)),
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post: ivec::slice(elts, idx + 1u,
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ivec::len(elts))});
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}
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_ { }
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}
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@ -113,7 +115,10 @@ fn elts_to_ell(cx: &ext_ctxt, elts: &[@expr])
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}
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idx += 1u;
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}
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ret {fixed: elts, rep: none};
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ret alt 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, U](f: &fn(&T) -> option::t[U] , v: &[T]) ->
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@ -275,8 +280,8 @@ fn transcribe_exprs(cx: &ext_ctxt, b: &bindings, idx_path: @mutable [uint],
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recur: fn(&@expr) -> @expr , exprs: [@expr])
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-> [@expr] {
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alt elts_to_ell(cx, exprs) {
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{fixed: fixed, rep: repeat_me_maybe} {
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let res = ivec::map(recur, fixed);
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{pre: pre, rep: repeat_me_maybe, post: post} {
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let res = ivec::map(recur, pre);
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alt repeat_me_maybe {
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none. {}
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some(repeat_me) {
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@ -324,6 +329,7 @@ fn transcribe_exprs(cx: &ext_ctxt, b: &bindings, idx_path: @mutable [uint],
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}
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}
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}
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res += ivec::map(recur, post);
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ret res;
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}
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}
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@ -440,14 +446,25 @@ fn p_t_s_rec(cx: &ext_ctxt, m: &matchable, s: &selector, b: &binders) {
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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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alt elts_to_ell(cx, p_elts) {
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{fixed: fixed, rep: some(repeat_me)} {
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if(ivec::len(fixed) > 0u) {
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p_t_s_r_actual_vector(cx, fixed, true, s, b);
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{pre: pre, rep: some(repeat_me), post: post} {
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p_t_s_r_length(cx, ivec::len(pre) + ivec::len(post),
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true, s, b);
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if(ivec::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, ivec::len(pre), s, b);
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if(ivec::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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p_t_s_r_ellipses(cx, repeat_me, ivec::len(fixed), s, b);
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}
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{fixed: fixed, rep: none.} {
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p_t_s_r_actual_vector(cx, fixed, false, s, b);
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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, ivec::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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@ -606,17 +623,17 @@ fn p_t_s_r_ellipses(cx: &ext_ctxt, repeat_me: @expr, offset: uint,
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compose_sels(s, bind select(cx, repeat_me, offset, _)), b);
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}
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fn p_t_s_r_actual_vector(cx: &ext_ctxt, elts: [@expr], repeat_after: bool,
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s: &selector, b: &binders) {
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fn len_select(cx: &ext_ctxt, m: &matchable, repeat_after: bool, len: uint)
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fn p_t_s_r_length(cx: &ext_ctxt, len: uint, at_least: bool, s: selector,
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b: &binders) {
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fn len_select(cx: &ext_ctxt, m: &matchable, at_least: bool, len: uint)
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-> match_result {
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ret alt m {
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match_expr(e) {
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alt e.node {
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expr_vec(arg_elts, _, _) {
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let actual_len = ivec::len(arg_elts);
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if (repeat_after && actual_len >= len)
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|| actual_len == len {
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if (at_least && actual_len >= len) || actual_len == len {
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some(leaf(match_exact))
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} else { none }
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}
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@ -627,10 +644,11 @@ fn p_t_s_r_actual_vector(cx: &ext_ctxt, elts: [@expr], repeat_after: bool,
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}
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}
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b.literal_ast_matchers +=
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~[compose_sels(s, bind len_select(cx, _, repeat_after,
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ivec::len(elts)))];
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~[compose_sels(s, bind len_select(cx, _, at_least, len))];
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}
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fn p_t_s_r_actual_vector(cx: &ext_ctxt, elts: [@expr], repeat_after: bool,
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s: &selector, b: &binders) {
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let idx: uint = 0u;
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while idx < ivec::len(elts) {
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fn select(cx: &ext_ctxt, m: &matchable, idx: uint) -> match_result {
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@ -678,7 +696,7 @@ fn add_new_extension(cx: &ext_ctxt, sp: span, arg: @expr,
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alt mac.node {
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mac_invoc(pth, invoc_arg, body) {
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alt path_to_ident(pth) {
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some(id) {
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some(id) {
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alt macro_name {
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none. { macro_name = some(id); }
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some(other_id) {
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@ -43,4 +43,9 @@ fn main() {
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assert (#transcr_mixed[10, 5, 4, 3, 2, 1] == 210);
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#macro[[#surround[pre, [xs, ...], post],
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[pre, xs, ..., post]]];
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assert (#surround[1, [2,3,4], 5] == [1,2,3,4,5]);
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}
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