liii_alist.tmu

<TMU|<tuple|1.0.5|1.2.9.8>>

<style|<tuple|generic|chinese|goldfish|literate|reduced-margins|python>>

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  <chapter|(liii alist)><label|chapter:liii_alist>

  <section|概述>

  alist-lib是Chicken Scheme中的函数库：

  <\description>
    <item*|文档><slink|https://wiki.call-cc.org/eggref/5/alist-lib>

    <item*|官网><slink|https://github.com/klutometis/alist-lib>
  </description>

  <section|许可证>

  <\goldfish-chunk|goldfish/liii/alist.scm|false|true>
    ;

    ; BSD License by Peter Danenberg

    ;

    \;
  </goldfish-chunk>

  <\goldfish-chunk|tests/goldfish/liii/alist-test.scm|false|true>
    ;

    ; Copyright (C) 2024 The Goldfish Scheme Authors

    ;

    ; Licensed under the Apache License, Version 2.0 (the "License");

    ; you may not use this file except in compliance with the License.

    ; You may obtain a copy of the License at

    ;

    ; http://www.apache.org/licenses/LICENSE-2.0

    ;

    ; Unless required by applicable law or agreed to in writing, software

    ; distributed under the License is distributed on an "AS IS" BASIS, WITHOUT

    ; WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the

    ; License for the specific language governing permissions and limitations

    ; under the License.

    ;

    \;
  </goldfish-chunk>

  \;

  <section|接口>

  <\goldfish-chunk|goldfish/liii/alist.scm|true|true>
    (define-library (liii alist)

    (import (liii base)

    \ \ \ \ \ \ \ \ (liii list)

    \ \ \ \ \ \ \ \ (liii error)

    \ \ \ \ \ \ \ \ (scheme case-lambda))

    (export alist? alist-cons alist-ref alist-ref/default vector-\<gtr\>alist)

    (begin

    \;
  </goldfish-chunk>

  <section|测试>

  <\scm-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (import (liii check)

    \ \ \ \ \ \ \ \ (liii alist))

    \;

    (check-set-mode! 'report-failed)

    \;
  </scm-chunk>

  <section|实现>

  <paragraph|alist?>

  如果一个列表中的每一个元素都是序对，那么该列表是关联列表。

  <\goldfish-chunk|goldfish/liii/alist.scm|true|true>
    (define (alist? l)

    \ \ (and (list? l)

    \ \ \ \ \ \ \ (every pair? l)))

    \;
  </goldfish-chunk>

  空列表是关联列表

  <\scm-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (check-true (alist? '()))

    \;
  </scm-chunk>

  下面是常见的关联列表

  <\scm-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (check-true (alist? '((a 1))))

    (check-true (alist? '((a . 1))))

    (check-true (alist? '((a . 1) (b . 2))))

    \;
  </scm-chunk>

  下面例子是列表，但不是关联列表：

  <\scm-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (check-false (alist? '(1 2 3)))

    \;
  </scm-chunk>

  \;

  <paragraph|alist-ref><index|alist-ref><scm|(alist key thunk =) =\<gtr\> object>

  alist-ref 是一个用于从关联列表（alist）中检索与给定键（key）相关联的值的函数。如果给定的键在列表中不存在，函数将执行一个提供的thunk（或错误处理函数），或者返回一个默认值。

  <subsubsection*|参数>

  <\itemize>
    <item><code*|alist>: 要搜索的关联列表。

    <item><code*|key>: 要检索的键。

    <item><code*|thunk> (可选): 当键不存在时执行的thunk。默认情况下，如果没有提供thunk，函数将抛出一个错误。

    <item><code*|=> (可选): 用于比较键的等价谓词。默认使用 <code*|eqv?>。
  </itemize>

  <subsubsection*|返回值>

  <itemize|<item>返回与给定键相关联的值，或者如果键不存在，则返回thunk的执行结果或默认值。>

  <\goldfish-chunk|goldfish/liii/alist.scm|true|true>
    (define alist-ref

    \ \ (case-lambda

    \ \ \ \ ((alist key)

    \ \ \ \ \ (alist-ref

    \ \ \ \ \ \ \ alist

    \ \ \ \ \ \ \ key

    \ \ \ \ \ \ \ (lambda () (key-error "alist-ref: key not found " key))))

    \ \ \ \ ((alist key thunk)

    \ \ \ \ \ (alist-ref alist key thunk eqv?))

    \ \ \ \ ((alist key thunk =)

    \ \ \ \ \ (let ((value (assoc key alist =)))

    \ \ \ \ \ \ \ (if value

    \ \ \ \ \ \ \ \ \ \ \ (cdr value)

    \ \ \ \ \ \ \ \ \ \ \ (thunk))))))

    \;
  </goldfish-chunk>

  <\scm-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (check (alist-ref '((a 1)) 'a) =\<gtr\> '(1))

    (check (alist-ref '((a . 1)) 'a) =\<gtr\> 1)

    (check-catch 'key-error (alist-ref '(("a" . 1)) "a"))

    (check-catch 'key-error (alist-ref '((a . 1)) 'b))

    \;

    (check (alist-ref '((a . 1)) 'b (lambda () 2)) =\<gtr\> 2)

    \;
  </scm-chunk>

  <paragraph|alist-ref/default><index|alist-ref/default><scm|(alist key default =) =\<gtr\> object>

  <\goldfish-chunk|goldfish/liii/alist.scm|true|true>
    (define alist-ref/default

    \ \ (case-lambda

    \ \ \ \ ((alist key default)

    \ \ \ \ \ (alist-ref alist key (lambda () default)))

    \ \ \ \ ((alist key default =)

    \ \ \ \ \ (alist-ref alist key (lambda () default) =))))

    \;
  </goldfish-chunk>

  <\goldfish-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (check (alist-ref/default '((a . 1)) 'b 2) =\<gtr\> 2)

    \;
  </goldfish-chunk>

  <paragraph|vector-\<gtr\>alist>

  <\goldfish-chunk|goldfish/liii/alist.scm|true|true>
    ; MIT License

    ; Copyright guenchi (c) 2018 - 2019

    (define vector-\<gtr\>alist

    \ \ (typed-lambda ((x vector?))

    \ \ \ \ (if (zero? (length x)) '()

    \ \ \ \ \ \ \ \ (let loop ((x (vector-\<gtr\>list x)) (n 0))

    \ \ \ \ \ \ \ \ \ \ \ \ \ (cons (cons n (car x))\ 

    \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (if (null? (cdr x))

    \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ '()

    \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (loop (cdr x) (+ n 1))))))))

    \ \ \ \ 
  </goldfish-chunk>

  <subparagraph|测试空向量>

  <\goldfish-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (check (vector-\<gtr\>alist #()) =\<gtr\> '())

    \;
  </goldfish-chunk>

  <subparagraph|测试单个元素向量>

  <\goldfish-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (check (vector-\<gtr\>alist #(42)) =\<gtr\> '((0 . 42)))

    \;
  </goldfish-chunk>

  <subparagraph|测试多个元素的向量>

  <\goldfish-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (check (vector-\<gtr\>alist #("a" "b" "c")) =\<gtr\> '((0 . "a") (1 . "b") (2 . "c")))

    \;
  </goldfish-chunk>

  <subparagraph|测试嵌套向量>

  <\goldfish-chunk|tests/goldfish/liii/alist-test.scm|true|true>
    (check (vector-\<gtr\>alist #(#(1 2) #(3 4))) =\<gtr\> '((0 . #(1 2)) (1 . #(3 4))))

    \;
  </goldfish-chunk>

  <section|结束>

  <\goldfish-chunk|goldfish/liii/alist.scm|true|false>
    ) ; end of begin

    ) ; end of library

    \;
  </goldfish-chunk>

  <\scm-chunk|tests/goldfish/liii/alist-test.scm|true|false>
    (check-report)

    \;
  </scm-chunk>

  \;
</body>

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