是否有精确的makefile语法定义？或者至少是一些常见的子集，因为我猜有一些口味。这样的语法可用于编写解析器。
GNU Make 手册似乎没有那么精确。根据该文档为 makefile 编写解析器需要一些猜测和反复试验。
我还在ANTLR mail list 上发现了一个类似的问题。但它仍然没有回答哪种暗示答案......
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3805 次
2 回答
14
似乎 gnu make 没有官方语法，并且...
为 make 编写语法会很棘手，因为语法非常依赖于上下文。
正如 Paul D. Smith 在gnu make mailing list 中的消息中所说。Paul D. Smith 是 gnu make 的官方维护者。
于 2013-08-28T15:06:52.250 回答
13
我为自己制作了 GNU Make 的语法，您可以在下面找到 lexer 的语法和概述。它并不完美，但它可以作为想要更好的人的起点。一些附加和背景信息在帖子中。
Bison的语法转储
/* Assign lower precedence to NL. */
/* %precedence NL */
/* %precedence COMMENT "ifdef" "ifndef" "ifeq" "ifneq" */
1 makefile: statements "end of file"
2 | "end of file"
3 statements: br
4 | statement
5 | statements br
6 | statements statement
7 conditional: if_eq_kw condition statements_opt "endif" comment_opt br
8 | if_eq_kw condition statements_opt "else" statements_opt "endif" comment_opt br
9 | if_eq_kw condition statements_opt "else" conditional
10 | if_def_kw identifier statements_opt "endif" comment_opt br
11 | if_def_kw identifier statements_opt "else" statements_opt "endif" comment_opt br
12 | if_def_kw identifier statements_opt "else" conditional
13 conditional_in_recipe: if_eq_kw condition recipes_opt "endif" comment_opt
14 | if_eq_kw condition recipes_opt "else" recipes_opt "endif" comment_opt
15 | if_eq_kw condition recipes_opt "else" conditional_in_recipe
16 | if_def_kw identifier recipes_opt "endif" comment_opt
17 | if_def_kw identifier recipes_opt "else" recipes_opt "endif" comment_opt
18 | if_def_kw identifier recipes_opt "else" conditional_in_recipe
19 condition: '(' expressions_opt ',' expressions_opt ')'
20 | SLIT SLIT
21 define: "define" pattern definition "endef" br
22 | specifiers "define" pattern definition "endef" br
23 | "define" pattern ASSIGN_OP definition "endef" br
24 | specifiers "define" pattern ASSIGN_OP definition "endef" br
25 definition: comment_opt br
26 | comment_opt br exprs_in_def br
27 include: "include" expressions br
28 statements_opt: comment_opt br
29 | comment_opt br statements
30 if_def_kw: "ifdef"
31 | "ifndef"
32 if_eq_kw: "ifeq"
33 | "ifneq"
34 statement: COMMENT
35 | assignment br
36 | function br
37 | rule
38 | conditional
39 | define
40 | include
41 | export br
42 export: "export"
43 | "unexport"
44 | assignment_prefix
45 | assignment_prefix WS targets
46 assignment: pattern ASSIGN_OP comment_opt
47 | pattern ASSIGN_OP exprs_in_assign comment_opt
48 | assignment_prefix ASSIGN_OP comment_opt
49 | assignment_prefix ASSIGN_OP exprs_in_assign comment_opt
50 assignment_prefix: specifiers pattern
51 specifiers: "override"
52 | "export"
53 | "unexport"
54 | "override" "export"
55 | "export" "override"
56 | "undefine"
57 | "override" "undefine"
58 | "undefine" "override"
59 expressions_opt: %empty
60 | expressions
61 expressions: expression
62 | expressions WS expression
63 exprs_nested: expr_nested
64 | exprs_nested WS expr_nested
65 exprs_in_assign: expr_in_assign
66 | exprs_in_assign WS expr_in_assign
67 exprs_in_def: first_expr_in_def
68 | br
69 | br first_expr_in_def
70 | exprs_in_def br
71 | exprs_in_def WS expr_in_recipe
72 | exprs_in_def br first_expr_in_def
73 first_expr_in_def: char_in_def expr_in_recipe
74 | function expr_in_recipe
75 | char_in_def
76 | function
77 exprs_in_recipe: expr_in_recipe
78 | exprs_in_recipe WS expr_in_recipe
79 expression: expression_text
80 | expression_function
81 expr_nested: expr_text_nested
82 | expr_func_nested
83 expr_in_assign: expr_text_in_assign
84 | expr_func_in_assign
85 expr_in_recipe: expr_text_in_recipe
86 | expr_func_in_recipe
87 expression_text: text
88 | expression_function text
89 expr_text_nested: text_nested
90 | expr_func_nested text_nested
91 expr_text_in_assign: text_in_assign
92 | expr_func_in_assign text_in_assign
93 expr_text_in_recipe: text_in_recipe
94 | expr_func_in_recipe text_in_recipe
95 expression_function: function
96 | '(' exprs_nested ')'
97 | expression_text function
98 | expression_function function
99 expr_func_nested: function
100 | '(' exprs_nested ')'
101 | expr_func_nested function
102 | expr_text_nested function
103 expr_func_in_assign: function
104 | expr_func_in_assign function
105 | expr_text_in_assign function
106 expr_func_in_recipe: function
107 | expr_func_in_recipe function
108 | expr_text_in_recipe function
109 function: VAR
110 | "$(" function_name ")"
111 | "$(" function_name WS arguments ")"
112 | "$(" function_name ',' arguments ")"
113 | "$(" function_name ':' expressions ")"
114 | "$(" function_name ASSIGN_OP expressions ")"
115 function_name: function_name_text
116 | function_name_function
117 function_name_text: function_name_piece
118 | function_name_function function_name_piece
119 function_name_piece: CHARS
120 | function_name_piece CHARS
121 function_name_function: function
122 | function_name_text function
123 arguments: %empty
124 | argument
125 | arguments ','
126 | arguments ',' argument
127 argument: expressions
128 rule: targets colon prerequisites NL
129 | targets colon prerequisites recipes NL
130 | targets colon assignment NL
131 target: pattern
132 pattern: pattern_text
133 | pattern_function
134 pattern_text: identifier
135 | pattern_function identifier
136 pattern_function: function
137 | pattern_text function
138 | pattern_function function
139 prerequisites: %empty
140 | targets
141 targets: target
142 | targets WS target
143 recipes: recipe
144 | recipes recipe
145 recipes_opt: comment_opt NL
146 | comment_opt recipes NL
147 recipe: LEADING_TAB exprs_in_recipe
148 | NL conditional_in_recipe
149 | NL COMMENT
150 identifier: CHARS
151 | ','
152 | '('
153 | ')'
154 | identifier CHARS
155 | identifier keywords
156 | identifier ','
157 | identifier '('
158 | identifier ')'
159 text: char
160 | text char
161 text_nested: char_nested
162 | text_nested char_nested
163 text_in_assign: char_in_assign
164 | text_in_assign char_in_assign
165 text_in_recipe: char_in_recipe
166 | text_in_recipe char_in_recipe
167 char: CHARS
168 | SLIT
169 | ASSIGN_OP
170 | ':'
171 char_nested: char
172 | ','
173 char_in_assign: char_nested
174 | '('
175 | ')'
176 | keywords
177 char_in_def: char
178 | '('
179 | ')'
180 | ','
181 | COMMENT
182 | "include"
183 | "override"
184 | "export"
185 | "unexport"
186 | "ifdef"
187 | "ifndef"
188 | "ifeq"
189 | "ifneq"
190 | "else"
191 | "endif"
192 | "define"
193 | "undefine"
194 char_in_recipe: char_in_assign
195 | COMMENT
196 keywords: "include"
197 | "override"
198 | "export"
199 | "unexport"
200 | "ifdef"
201 | "ifndef"
202 | "ifeq"
203 | "ifneq"
204 | "else"
205 | "endif"
206 | "define"
207 | "endef"
208 | "undefine"
209 br: NL
210 | LEADING_TAB
211 colon: ':'
212 | ':' ':'
213 comment_opt: %empty
214 | COMMENT
一些词法分析器细节
- 所有的
'和几乎所有的"引号都是文字。 ')' ::= <unpaired )>'}' ::= <unpaired }>"$(" ::= "$(" | "${"– 扩张的开始")" ::= ")" | "}"– 扩展的结束"end of file" ::= <end of file>COMMENT ::= <# comment (can be multiline)>ASSIGN_OP ::= "=" | "?=" | ":=" | "::=" | "+=" | "!="CHARS ::= <sequence of non-whitespace>WS ::= <sequence of whitespace>NL ::= "\n" | "\r" | "\r\n"VAR ::= /\$./SLIT ::= <single- or double-quote literal>LEADING_TAB ::= <tabulation at the first position in a line (eats NL)>
空格处理很棘手：词法分析器应该忽略它，除非先前返回的令牌需要它后面的空格。
)展开式 (或) 的不成对闭合部分}就是它们本身。虽然$(...)or的内容${...}永远不是关键字。
解决混乱
两条评论表达了同样的问题：
另一方面，您
make确实以某种方式解析了makefile并允许一些并拒绝其他...
您不需要语法来解析语言。但是，拥有它是一件好事。
一般来说，可能的语言比形式语法多，因为语法具有排除某些语言的约束。
我猜make它在管理状态的同时读取输入并同时处理它，这样它在每一点都知道它接下来可以接受什么样的输入以及如何处理它。正式语言倾向于与上下文无关，这意味着它们不会保留太多关于其状态的记录。正是这种差距使得 's 语言很难形式化make，即使在没有语法的情况下实现它仍然是可能的。
于 2019-02-28T17:03:05.730 回答