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e16a7d8f3b
`et` means `expandtab`. ```sh rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\) et\(.*\) :vi/vi: \1 xoet\2:vi/' rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\)noet\(.*\):vi/vi: \1et\2 :vi/' rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\)xoet\(.*\):vi/vi: \1noet\2:vi/' ```
96 lines
4.5 KiB
C
96 lines
4.5 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "tool/plinko/lib/histo.h"
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#include "tool/plinko/lib/index.h"
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#include "tool/plinko/lib/plinko.h"
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#include "tool/plinko/lib/tree.h"
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/**
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* Performs lookup of binding.
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*
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* We perform lookups into an association list, e.g.
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*
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* ┌───┬───┐ ┌───┬───┐ ┌───┬───┐
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* │ 𝑘₀│ 𝑣₀│ │ 𝑘₁│ 𝑣₁│ │ 𝑘₂│ 𝑣₂│
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* └─┬─┴───┘ └─┬─┴───┘ └─┬─┴───┘
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* ┌─│─┬───┐ ┌─│─┬───┐ ┌─│─┬───┐
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* 𝑎=│ ┴ │ ├───┤ ┴ │ ├───┤ ┴ │ 0 │
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* └───┴───┘ └───┴───┘ └───┴───┘
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*
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* For example, if 𝑘₁ is queried then we return:
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*
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* ┌───┬───┐
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* │ 𝑘₁│ 𝑣₁│
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* └───┴───┘
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*
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* However there's a twist: the association is allowed to turn into a
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* red-black tree. That would look like this:
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*
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* ┌───┬───┐ ┌───┬───┐
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* │ 𝑘₀│ 𝑣₀│ │ 𝑘₁│ 𝑣₁│
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* └─┬─┴───┘ └─┬─┴───┘
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* ┌─│─┬───┐ ┌─│─┬───┐ ┌───┬───┐
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* 𝑎=│ ┴ │ ├───┤ ┴ │ ├───│ ┬ │ 𝑐 │
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* └───┴───┘ └───┴───┘ └─│─┴───┘
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* ┌─┴─┬───┐
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* │ ┬ │ ┬ │
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* └─│─┴─│─┘
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* ┌───┬──┴┐ ┌┴──┬───┐
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* │ 𝑘₂│ 𝑣₂│ │ L │ R │
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* └───┴───┘ └───┴───┘
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*
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* We're able to tell a tree node apart from an association list node
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* because we make the assumption that 𝑘ᵢ is an atom. On the other hand
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* 𝑣ᵢ can be anything.
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*
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* @param k is an atom
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* @param a is an association list and/or red-black tree
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* @return entry cons cell or 0 if not found
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*/
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int Assoc(int k, int a) {
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int i, j, e, c, r;
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DCHECK_GE(k, 0);
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i = a;
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r = 0;
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if (k && k != 1) {
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for (c = 0; i;) {
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e = Head(i);
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i = Cdr(i);
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j = Head(e);
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++c;
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if (j == k) {
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r = e;
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break;
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} else if (j < 0 && (j =
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#if HISTO_ASSOC
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GetTreeCount(k, e, &c)
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#else
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GetTree(k, e)
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#endif
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)) {
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r = Ent(j);
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break;
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}
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}
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#if HISTO_ASSOC
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HISTO(g_assoc_histogram, c);
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#endif
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}
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return r;
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}
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