Compiler construction 删除可为空的产品
我正在为pascal的子集创建一个词法分析器,这是编译器红龙教科书后面推荐的一个编程项目。我正在将语法更改为LL,以便创建解析表。我忽略了犹豫不决的模糊性,并且相信这是唯一存在的模糊性。我刚刚删除了所有的epsilon产品。在我继续进行左因子分解之前,我想得到一些关于我是否正确删除了ε乘积的反馈。我已经盯着这个看了很长一段时间了,所以我真的不确定我是否错过了一些会在以后引起问题的东西,并且没有人来检查它。我知道这是一个很长的帖子,我真的不知道去哪里让知道的人检查。我真的很感谢你的时间 原始语法:Compiler construction 删除可为空的产品,compiler-construction,ll,epsilon,Compiler Construction,Ll,Epsilon,我正在为pascal的子集创建一个词法分析器,这是编译器红龙教科书后面推荐的一个编程项目。我正在将语法更改为LL,以便创建解析表。我忽略了犹豫不决的模糊性,并且相信这是唯一存在的模糊性。我刚刚删除了所有的epsilon产品。在我继续进行左因子分解之前,我想得到一些关于我是否正确删除了ε乘积的反馈。我已经盯着这个看了很长一段时间了,所以我真的不确定我是否错过了一些会在以后引起问题的东西,并且没有人来检查它。我知道这是一个很长的帖子,我真的不知道去哪里让知道的人检查。我真的很感谢你的时间 原始语法:
<statement> →
if <expression> then <statement>
<factor> → id
<program> →
<program> id (<identifier_list>);
<declarations>
<subprogram_declarations>
<compound_statement>
.
<identifier_list> →
id
| <identifier_list>, id
<declarations> →
<declarations> var id : <type>;
|E
<type> →
<standard_type>
|array[num..num] of <standard_type>
<standard type> →
integer
| real
<subprogram_declarations> →
<subprogram_declarations> <subprogram_declaration>;
|E
<subprogram_declaration> →
<subprogram_head declarations>
<subprogram_declarations>
<compound_statement>
<subprogram_head> →
function id <arguments> : <standard_type>;
<arguments> →
(<parameter_list>)
| E
<parameter_list> →
id : <type>
| <parameter_list>; id : <type>
<compound statement> →
begin
<optional_statements>
end
<optional_statements> →
<statement_list>
| E
<statement_list> →
<statement>
|<statement_list>; <statement>
<statement> →
<variable> assignop <expression>
| <procedure_statement>
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<variable> →
id
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<expression_list> →
<expression>
|<expression_list> , <expression>
<expression> →
<simple_expression>
| <simple_expression> relop <simple_expression>
<simple_expression> →
<term>
| sign <term>
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<term> →
<factor>
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<factor> →
id
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<sign> →
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→
若然
→ 身份证件
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身份证件
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身份证件:
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开始
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身份证件
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→
|穆洛普
→
身份证件
|id()
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→
+ | -
语法后ε产生消除
<statement> →
if <expression> then <statement>
<factor> → id
<program> →
<program><id (<identifier_list>);
<declarations>
<subprogram_declarations>
.
|<program> id (<identifier_list>);
<subprogram_declarations>
.
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.
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.
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<declarations>
<subprogram_declarations>
begin
<statement_list>
end
.
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<subprogram_declarations>
begin
<statement_list>
end
.
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begin
<statement_list>
end
.
|<program> id (<identifier_list>);
begin
<statement_list>
end
.
<identifier_list> →
id
| <identifier_list>, id
<declarations> →
<declarations> var id : <type>;
<type> →
<standard_type>
|array[num..num] of standard_type
<standard type> →
<integer>
| <real>
<subprogram_declarations> →
<subprogram_declarations> <subprogram_declaration>;
<subprogram_declaration> →
<subprogram_head> <declarations>
<subprogram_declarations >
begin
<statement_list>
end
|<subprogram_head>
<subprogram_declarations >
begin
<statement_list>
end
|<subprogram_head> <declarations>
begin
<statement_list>
end
|<subprogram_head>
begin
<statement_list>
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|<subprogram_head>
<subprogram_declarations >
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|<subprogram_head>
<subprogram_head> →
function id (<parameter_list>) : <standard_type>;
|function id : <standard_type>;
<parameter_list> →
id : <type>
|<parameter_list>; id : <type>
<statement_list> →
<statement>
|<statement_list>;< statement>
<statement> →
<variable> assignop <expression>
| <procedure_statement>
| <compound_statement>
| if <expression> then <statement> else <statement>
| while <expression> do <statement>
| if <expression> then <statement>
<variable> →
id
|id [<expression>]
<expression_list> →
<expression>
|<expression_list> , <expression>
<expression> →
<simple_expression>
| <simple_expression> relop <simple_expression>
<simple_expression> →
<term>
| <sign> <term>
| <simple_expression> addop <term>
<term> →
<factor>
| <term> mulop <factor>
<factor> →
id
| id (<expression_list>)
| num
| (<expression>)
| not <factor>
| id [<expression>]
<sign> →
+ | -
→
若然
→ 身份证件
→
<subprogram_head> →
function id <arguments> : <standard_type>;
<arguments> →
(<parameter_list>)
| E
<subprogram_head> →
function id (<parameter_list>) : <standard_type>;
|function id : <standard_type>;