使用ocamlyacc从不减少规则

我在用ocaml编译lexer时遇到一个警告：

File "lexer.mll", line 42, characters 26-57:
Warning 10: this expression should have type unit.

我想解析字符串，我制定了一个特殊的规则，当lexer读取一个引号时开始，当我读取另一个引号时结束，在这种情况下，返回字符串并为每个其他字符调用规则标记

以下是文件：

{
    open Int32
    open Lexing
    open Parser

    exception LexicalError of string * Lexing.position * Lexing.position

    let string = Buffer.create 50

    let error s lexbuf =
       raise (LexicalError(s, Lexing.lexeme_start_p lexbuf, Lexing.lexeme_end_p lexbuf))


    let kwords = [ "boolean", BOOLEAN; "class", CLASS; "else", ELSE;
                   "extends", EXTENDS; "for", FOR; "if", IF; "instanceof",
                   INSTANCEOF; "int", INT; "new", NEW; "null", NULL;  "public",
                   PUBLIC; "return", RETURN; "static", STATIC; "this", THIS;
                   "void", VOID; "String", STRING; ]

    let ident_or_kword s = 
       try
          List.assoc s kwords
       with
          Not_found -> IDENT(s)
}

let blank = [' ' '\t' '\n']+
let digit = ['0'-'9']
let alpha = ['a'-'z''A'-'Z']
let ident = ((alpha | '_')(alpha | '_' | digit)*)
let car   = [' '-'~']
let end_quote = '"'

rule comment = parse
| "*/"                  { token lexbuf }
| eof                   { error "End Of File" lexbuf }
| _                     { comment lexbuf } 

and chaine = parse
| end_quote             { CSTRING(Buffer.contents string); token lexbuf }
| car as c              { Buffer.add_char string c; token lexbuf }
| eof                   { error "End Of File" lexbuf }
| _ as c                { error (String.make 1 c) lexbuf }

and token = parse
| blank                 { token lexbuf }
| "/*"                  { comment lexbuf }
| ident as id           { ident_or_kword id }
| '"'                   { chaine lexbuf }
| '.'                   { MEMBER }
| '='                   { ASSIGN }
| "=="                  { EQ }
| "!="                  { DIFF }
| '<'                   { LESS }
| "<="                  { LESS_EQ }
| '>'                   { GREATER }
| ">="                  { GREATER_EQ }
| "++"                  { PLUS_PLUS }
| '+'                   { PLUS }
| "--"                  { MINUS_MINUS }
| '-'                   { MINUS }
| '*'                   { TIMES }
| '/'                   { DIV }
| '%'                   { MOD }
| "&&"                  { AND }
| "||"                  { OR }
| '!'                   { BANG }
| '('                   { LP }
| ')'                   { RP }
| '{'                   { LB }
| '}'                   { RB }
| '['                   { LC }
| ']'                   { RC }
| ';'                   { SC }
| ','                   { COMMA }
| "true|false" as bool  { CBOOL(bool_of_string bool) }
| digit+ as int         {
             try
                 CINT(of_string int)
             with
                 _ -> error int lexbuf }
| eof                   { EOF }
| _ as c                { error (String.make 1 c) lexbuf }

{
打开Int32
开放词法
开放解析器
字符串*Lexing.position*Lexing.position的异常词典错误
让string=Buffer.create 50
让错误s lexbuf=
raise（词汇错误（s，Lexing.lexeme\u start\u p lexbuf，Lexing.lexeme\u end\u p lexbuf））
让kwords=[“boolean”，boolean；“class”，class；“else”，else；
“扩展”，扩展；“for”，for；“if”，if；“instanceof”，
INSTANCEOF；“int”，int；“new”，new；“null”，null；“public”，
公共；“返回”，返回；“静态”，静态；“此”，此；
“void”，void；“String”，String；]
设ident_或_kword s=
尝试
列表.assoc s kwords
具有
未找到->标识
}
让blank=['''\t'\n']+
让数字=['0'-'9']
设alpha=['a'-'z''a'-'z']
设ident=（（alpha |'|'|'）（alpha |'|'|位）*）
let car=[''-'~']
让我们以“=”结尾
规则注释=解析
|“*/”{token lexbuf}
|eof{error“文件结尾”lexbuf}
|{comment lexbuf}
和chaine=parse
|end_quote{CSTRING（Buffer.contents string）；token lexbuf}
|car作为c{Buffer.add_char string c；token lexbuf}
|eof{error“文件结尾”lexbuf}
|_uASC{error（String.make 1 c）lexbuf}
and token=parse
|空白{token lexbuf}
|“/*”{comment lexbuf}
|标识为id{ident_或_kword id}
|“{chaine lexbuf}
|“.{成员}”
|'='{ASSIGN}
|“==”{EQ}
|“！=”{DIFF}
|“{更大}”
|“>=”{GREATER_EQ}
|“++”{PLUS_PLUS}
|“+”{PLUS}
|“--”{负{u负}
|'-'{负}
|'*'{TIMES}
|“/”{DIV}
|“%”{MOD}
|“&&”{AND}
|“| |”{或}
| '!'                   {BANG}
|“（{LP}
|“）”{RP}
|{{LB}
|'}{RB}
|'['{LC}
|']'{RC}
| ';'                   {SC}
|“，”{COMMA}
|“true | false”作为bool{CBOOL（bool_of_string bool）}
|数字+整数{
尝试
CINT（由字符串int组成）
具有
_->错误int-lexbuf}
|eof{eof}
|_uASC{error（String.make 1 c）lexbuf}

我无法尝试您的代码，因为我没有您的解析器模块

在我看来，你需要这个：

| end_quote             { CSTRING(Buffer.contents string) }

在代码中，编译器抱怨此表达式不是

unit

类型。事实上，它的值是一个令牌，这是您想要返回的。我敢肯定，现在没有必要打电话给扫描仪。你已经有你的代币了