git.kianting.info Git - uann/blob - ocaml_yacc/parser.mly

   1 /* File parser.mly */
   2 %token <string> INT
   3 %token <string> ID
   4 %token PLUS MINUS TIMES DIV
   5 %token LPAREN RPAREN ASSIGN IN IMPLY FUNC
   6 %token EOL
   7 %right IMPLY FUNC
   8 %left PLUS MINUS/* lowest precedence */
   9 %left TIMES DIV /* medium precedence */
  10 %nonassoc UMINUS/* highest precedence */
  11 %start main     /* the entry point */
  12 %type <Ast.ast> main
  13 %%
  14 main:
  15     blocks EOL{  $1 }
  16 ;
  17 blocks:
  18 block{  $1 }
  19 |blocks block{match $1 with Ast.Node x -> Ast.Node (x @ [$2])
  20                                 | Ast.Int x -> Ast.Node[$1; $2] | Ast.Leaf x -> Ast.Node [$1; $2]} /* It Must not be entered */
  21 ;
  22
  23 block:
  24   expr {$1}
  25 | let_bind {$1}
  26 ;
  27
  28 let_bind:
  29 | typ ID ASSIGN expr IN block {Ast.Node [Ast.Leaf "%let"; Ast.Node[$1; Ast.Leaf $2; $4]; $6]}
  30 ;
  31
  32 typ:
  33 | ID {Ast.Leaf $1}
  34 | typ IMPLY typ {Ast.Node [Ast.Leaf "->"; $1 ; $3]}
  35
  36 expr:
  37  app_expr {$1}
  38 | bin_expr {$1}
  39 | lam_expr{$1}
  40 ;
  41
  42 lam_expr:
  43 arg FUNC block {Ast.Node [Ast.Leaf "%lambda"; $1 ; $3]}
  44 ;
  45 arg:
  46 typ ID { Ast.Node [$1;Ast.Leaf $2] }
  47 ;
  48
  49 app_expr:
  50  expr expr { Ast.Node [ Ast.Leaf "%apply"; $1; $2] }
  51 ;
  52 ;
  53 bin_expr:
  54     INT     { Ast.Int (int_of_string $1)}
  55   |  ID     { Ast.Leaf $1 }
  56   | LPAREN expr RPAREN      { $2 }
  57   | expr PLUS expr  { Ast.Node [ Ast.Leaf "+"; $1; $3] }
  58   | expr MINUS expr { Ast.Node[ Ast.Leaf "-"; $1 ; $3] }
  59   | expr TIMES expr { Ast.Node[ Ast.Leaf "*"; $1 ;$3] }
  60   | expr DIV expr   { Ast.Node[ Ast.Leaf "/"; $1; $3] }
  61   | MINUS expr %prec UMINUS { Ast.Node[ Ast.Leaf  "-" ; $2] }
  62 ;
  63