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on-keydayclaude
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ast: let a path end at a vector
A vector segment had to be followed by an index, so there was no way to ask for the vector to iterate it. Ending the path there now yields a pointer to it, the same shape a scalar already gave. fmt.field<"body.elements">() // std::vector<Node<Statement>>* fmt.field<"body.elements.0">() // Ref<Statement> .optional on a vector is rejected rather than supported: it would return the vector by value, and whether the path resolved is already answered by the pointer. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
1 parent 40a3c15 commit bc1a7f6

3 files changed

Lines changed: 30 additions & 1 deletion

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‎src/core/nast/access.h‎

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,7 @@
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// auto body = fmt.field<"body">(); // Ref<Body> (Ref は arena を持つ)
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// auto st = fmt.field<"body.struct_type">(); // Ref<StructType>
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// auto f0 = fmt.field<"body.elements.0">(); // Ref<Statement>
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// auto all = fmt.field<"body.elements">(); // std::vector<Node<Statement>>*
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// auto name = fmt.field<"name.identifier">(); // std::string*
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// auto st2 = node.field<"body.struct_type">(arena); // Node は arena を渡す
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// auto id = fmt.field<"name.identifier.optional">(); // std::optional<std::string>
@@ -139,11 +140,21 @@ namespace brgen::nast {
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return walk<Rest, U>(a, a.template get<U>(member));
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}
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}
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else if constexpr (vec::is_vector && is_empty<Rest>()) {
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// 配列そのもの。スカラーと同じくポインタで返す (回すのに要る)。
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return &member;
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}
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else if constexpr (vec::is_vector && is_optional_marker<Rest>()) {
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// 値で返すと配列を複製することになる。null かどうかは
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// ポインタ形で判定できるので、そちらを使わせる。
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static_assert(!is_optional_marker<Rest>(),
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"a vector cannot take .optional; drop it and check the pointer");
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}
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else if constexpr (vec::is_vector) {
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using U = typename vec::type;
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constexpr auto idx_seg = head<Rest>();
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static_assert(all_digit(idx_seg.view()),
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"a vector field must be followed by an array index");
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"a vector field must be followed by an array index, or end the path here");
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constexpr auto i = to_index<idx_seg>();
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constexpr auto after = tail<Rest>();
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if (member.size() <= i) {

‎src/core/nast/bind/binder.cpp‎

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
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/*license*/
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#pragma once
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#include "../nodes.h"
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#include "../access.h"
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namespace brgen::nast::bind {
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struct Binder {
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Arena& a;
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void bind(Node<Module> mod) {
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for (auto& bound : mod.ref(a)->statements) {
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}
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}
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};
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} // namespace brgen::nast::bind

‎src/core/nast/test.cpp‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -241,6 +241,9 @@ int main(int argc, char** argv) {
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"field<> follows Node fields through the arena, from Ref and from Node");
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check(f.field<"body.elements.0">().id() == fld.id(),
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"field<> indexes into a vector field");
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auto* elems = f.field<"body.elements">();
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check(elems && elems->size() == 1 && (*elems)[0] == fld.id(),
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"ending the path at a vector gives the vector itself");
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check(!f.field<"body.elements.9">(),
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"out of range index yields a null ref, not a crash");
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auto* ident = f.field<"name.identifier">();

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