如何將優先級設置爲規則？

Question

我寫的規則，但我不明白爲什麼慾望規則不匹配，因爲文檔對此表示：

When the generated scanner is run, it analyzes its input looking for strings 
which match any of its patterns. If it finds more than one match, it takes the 
one matching the most text (for trailing context rules, this includes the length 
of the trailing part, even though it will then be returned to the input). If it 
finds two or more matches of the same length, the rule listed first in the flex 
input file is chosen. 

我也看到了這個答案，但它沒有幫助：Is it possible to set priorities for rules to avoid the "longest-earliest" matching pattern?

... 
ANY_CHAR . 
... 

%% 
"gago"       { BEGIN V_TYPE; } 
<V_TYPE>"If"     { printf("print If");  exit(1);} 
<V_TYPE>"Then"     { printf("print Then");  exit(1);} 
<V_TYPE>"Endif"    { printf("print Endif"); exit(1);} 
<V_TYPE>"While"    { printf("print While"); exit(1);} 
<V_TYPE>"EndWhile"    { printf("print EndWhile"); exit(1);} 
<V_TYPE>{ANY_CHAR}*   { printf("print Other"); exit(1);} 

簡單的輸入：

gago 
EndWhile 

希望的輸出：

print EndWhile 

實際輸出：

print Other 

Answer 1

如果輸入是真的在兩個不同的線，那麼你的ANY_CHAR規則匹配換行符。如果你不關心換行符，你應該忽略它們。根據David Gorsline的評論，我還建議在ANY_CHAR上刪除*修飾符。

... 
ANY_CHAR . 
NEW_LINE [\n\r] 
... 

%% 
"gago"       { BEGIN V_TYPE; } 
<V_TYPE>"If"     { printf("print If");  exit(1);} 
<V_TYPE>"Then"     { printf("print Then");  exit(1);} 
<V_TYPE>"Endif"    { printf("print Endif"); exit(1);} 
<V_TYPE>"While"    { printf("print While"); exit(1);} 
<V_TYPE>"EndWhile"    { printf("print EndWhile"); exit(1);} 
<V_TYPE>{NEW_LINE}+   { /* ignore */ } 
<V_TYPE>{ANY_CHAR}    { printf("print Other"); exit(1);}