Snobol4 语言 提取 Markdown 中的链接列表

提取 Markdown 中的链接列表：Snobol4 语言实践

Markdown 是一种轻量级标记语言，常用于格式化文本，广泛应用于博客、文档和邮件中。Markdown 文档中常包含链接，用于引用外部资源或指向其他页面。Snobol4 是一种古老的编程语言，以其简洁和强大的文本处理能力而闻名。本文将探讨如何使用 Snobol4 语言编写一个模型，以提取 Markdown 文档中的链接列表。

Snobol4 简介

Snobol4 是一种高级编程语言，由 Stephen C. Johnson 在 1962 年设计。它以其强大的字符串处理能力而著称，特别适合于文本处理任务。Snobol4 的语法简洁，易于理解，但同时也具有一些独特的特性，如模式匹配和动态数组。

Markdown 链接格式

Markdown 中的链接通常遵循以下格式：


[链接文本](链接地址 "链接标题")


例如：


[Google](https://www.google.com "访问 Google")


Snobol4 提取链接列表

为了提取 Markdown 文档中的链接列表，我们需要编写一个 Snobol4 程序，该程序能够识别并提取上述格式的链接。

1. 定义模式

我们需要定义一个模式来匹配 Markdown 链接的格式。在 Snobol4 中，我们可以使用以下模式：

snobol
[ ^[] ] ( [ ^[] ] ) ( " [ ^"] " )?


这个模式解释如下：

- `[ ^[] ]`：匹配方括号内的任意非空格字符序列。
- ` " [ ^"] " `：可选地匹配引号内的任意非引号字符序列，表示链接标题。

2. 编写 Snobol4 程序

以下是一个简单的 Snobol4 程序，用于提取 Markdown 文档中的链接列表：

```snobol
:in
[ ^[] ] ( [ ^[] ] ) ( " [ ^"] " )?
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