业务规则引擎词法分析

文档字数:13626,页数:38  有开题报告，任务书

摘   要

 编译程序的工作贯穿从输入源程序开始到输出目标程序为止的整个过程，是非常复杂的。一般来说，整个过程可以划分为五个阶段：词法分析、语法分析、中间代码生成、优化和目标代码生成。
 本设计即为词法分析阶段。词法分析阶段是编译过程的第一个阶段。这个阶段的任务是从左至右扫描源程序的字符串，按照词法规则（正则文法规则）识别出一个个正确的单词，并转换成该单词相应的二元式（种别码、属性值）交给语法分析使用。因此，词法分析是编译的基础。执行词法分析的程序称为词法分析器。
 词法分析是从输入的源程序中，识别出每个具有独立意义的单词，即基本保留字（关键字）、标识符、常数、运算符、分隔符五大类，剔除空格与转义字符，并依次输出各个单词的内部编码及单词符号自身值。

关键词：词法分析；原词；编译原理；记号
Business rules engine Lexical Analysis

Abstract

 Compiler runs through the work started from the source input to output targets procedures of the whole process is very complex. Generally, the whole process can be divided into five phases: lexical analysis, grammar analysis, intermediate code generation, optimization and target code generation.
 This is the lexical analysis of the design stage. Lexical analysis stage is to build the first phase of the process. This phase of the mission is scanned from left to right source of the string, in accordance with the rules of morphology (Regular Grammar rules) to identify the correct one word, and converted into the corresponding dual-word (category codes, property values ) To the analysis of the use of grammar. Therefore, the lexical analysis is compiled based. Lexical analysis of the implementation of the procedure known as the lexical analyzer.
 Lexical analysis is imported from the source, identify each has an independent significance of the word, namely, the basic reservations about the word (keywords), the identifier, constant, the operator, separators top-five, remove spaces and escape, And the words were out of the internal code words and symbols its own value.

Key Words:  Lexical analysis; Vocable; Compilers; Principles; Token
目       录
1. 绪论 1
1.1课题背景及来源 1
1.2课题研究的目标及意义 1
1.3编译器发展历史及前景 2
1.4本文档组织结构 3
2. 项目介绍及方案概述 4
2.1编译器的构造 4
2.1.1编译程序的引进 4
2.1.2编译程序的功能 4
2.1.3编译程序的构造 5
2.2词法分析器构造实践之必要性 5
3. 业务规则引擎词法分析之过程分析 6
3.1扫描处理 6
3.2正则表达式 8
3.3有穷自动机 9
3.4从正则表达式到DFA 10
3.4.1从正则表达式到NFA 11
3.4.2从NFA到DFA 12
3.4.3利用子集构造模拟NFA 13
3.4.5将DFA中的状态数最小化 13
4. 词法分析器的设计与实现 15
4.1词法分析器设计目的 15
4.2词法分析器设计要求 15
4.3算法设计思想 15
4.3.1 Token编码 15
4.3.2函数构成 19
4.3.3注意事项 23
4.4词法分析流程图 23
4.4.1词法分析输入输出总体流程图 23
4.4.2判断标识符和数字的流程图 25
4.4.3函数dealword判别字符串流程图 25
4.5词法分析结果 28
4.5.1正确分析结果 28
4.5.2异常处理结果 28
4.5.3词法分析结果界面显示 29
5. 总结 31
致谢 32
参考文献 33

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