April 2014
Beginner to intermediate
830 pages
15h 21m
Chinese
Content preview from Mathematica 錦囊妙計
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5.11 實作語法分析器（Parser）與文法
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231
分析可能為空的形容詞串列
形容詞串列文法，
介系詞子句文法，
分析副詞串列（也可能沒有）
副詞串列文法，
[Page-231]
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232
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第五章
使用遵守此文法的語句對語法分析器進行測試。[Page-232]
討論說明
你可能會覺得奇怪，既然要手工打造語法分析器，為什麼還要費力建立文法。首先，此
分析器並不是我撰寫的，我只是把 Daniel Lichtblau 的分析器美化一番，正經一點的理
由是，除了語法分析器，文法也可以用來建立語言生成器，生成器對於測試分析器十
分有用。以下根據 Lichtblau 實作的生成器，加以改造一番。因為善用了 Mathematica
模式匹配的功能，首先改善的 是，本文 的實作是陳述式的（declarative）而非程序式
的（procedural）。其次是生成器吸收了程式複雜度，因此文法可以繼續保持簡潔。在
Lichtblau 原本的文法中，由於程式建構的理由，文法表示非常的麻煩，例如
Hold[]
指
令及隨機選擇的實作方式。除了機率的存在外，前文所建構的文法非常乾淨，事實上它
跟 BNF 一樣易讀。如果讀者想要比較我的版本與原始的實作版本，請參考「 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.