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(******************************************************************)
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(* GENERATED FILE -- DO NOT EDIT -- GENERATED FILE -- DO NOT EDIT *)
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(* GENERATED FILE -- DO NOT EDIT -- GENERATED FILE -- DO NOT EDIT *)
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(* GENERATED FILE -- DO NOT EDIT -- GENERATED FILE -- DO NOT EDIT *)
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(******************************************************************)
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print_depth 0;
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(*
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This file is generated from the contents of ML-Yacc's lib directory.
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ML-Yacc's COPYRIGHT-file contents follow:
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ML-YACC COPYRIGHT NOTICE, LICENSE AND DISCLAIMER.
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Copyright 1989, 1990 by David R. Tarditi Jr. and Andrew W. Appel
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Permission to use, copy, modify, and distribute this software and its
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documentation for any purpose and without fee is hereby granted,
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provided that the above copyright notice appear in all copies and that
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both the copyright notice and this permission notice and warranty
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disclaimer appear in supporting documentation, and that the names of
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David R. Tarditi Jr. and Andrew W. Appel not be used in advertising
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or publicity pertaining to distribution of the software without
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specific, written prior permission.
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David R. Tarditi Jr. and Andrew W. Appel disclaim all warranties with regard to
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this software, including all implied warranties of merchantability and fitness.
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In no event shall David R. Tarditi Jr. and Andrew W. Appel be liable for any
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special, indirect or consequential damages or any damages whatsoever resulting
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from loss of use, data or profits, whether in an action of contract, negligence
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or other tortious action, arising out of or in connection with the use or
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performance of this software.
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*)
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(**** Original file: base.sig ****)
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(* ML-Yacc Parser Generator (c) 1989 Andrew W. Appel, David R. Tarditi *)
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(* base.sig: Base signature file for SML-Yacc. This file contains signatures
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that must be loaded before any of the files produced by ML-Yacc are loaded
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*)
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(* STREAM: signature for a lazy stream.*)
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signature STREAM =
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sig type 'xa stream
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val streamify : (unit -> '_a) -> '_a stream
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val cons : '_a * '_a stream -> '_a stream
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val get : '_a stream -> '_a * '_a stream
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end
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(* LR_TABLE: signature for an LR Table.
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The list of actions and gotos passed to mkLrTable must be ordered by state
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number. The values for state 0 are the first in the list, the values for
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state 1 are next, etc.
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*)
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signature LR_TABLE =
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sig
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datatype ('a,'b) pairlist = EMPTY | PAIR of 'a * 'b * ('a,'b) pairlist
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datatype state = STATE of int
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datatype term = T of int
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datatype nonterm = NT of int
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datatype action = SHIFT of state
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| REDUCE of int
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| ACCEPT
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| ERROR
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type table
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val numStates : table -> int
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val numRules : table -> int
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val describeActions : table -> state ->
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(term,action) pairlist * action
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val describeGoto : table -> state -> (nonterm,state) pairlist
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val action : table -> state * term -> action
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val goto : table -> state * nonterm -> state
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val initialState : table -> state
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exception Goto of state * nonterm
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val mkLrTable : {actions : ((term,action) pairlist * action) array,
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gotos : (nonterm,state) pairlist array,
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numStates : int, numRules : int,
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initialState : state} -> table
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end
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(* TOKEN: signature revealing the internal structure of a token. This signature
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TOKEN distinct from the signature {parser name}_TOKENS produced by ML-Yacc.
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The {parser name}_TOKENS structures contain some types and functions to
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construct tokens from values and positions.
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The representation of token was very carefully chosen here to allow the
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polymorphic parser to work without knowing the types of semantic values
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or line numbers.
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This has had an impact on the TOKENS structure produced by SML-Yacc, which
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is a structure parameter to lexer functors. We would like to have some
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type 'a token which functions to construct tokens would create. A
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constructor function for a integer token might be
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INT: int * 'a * 'a -> 'a token.
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This is not possible because we need to have tokens with the representation
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given below for the polymorphic parser.
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Thus our constructur functions for tokens have the form:
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INT: int * 'a * 'a -> (svalue,'a) token
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This in turn has had an impact on the signature that lexers for SML-Yacc
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must match and the types that a user must declare in the user declarations
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section of lexers.
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*)
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signature TOKEN =
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sig
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structure LrTable : LR_TABLE
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datatype ('a,'b) token = TOKEN of LrTable.term * ('a * 'b * 'b)
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val sameToken : ('a,'b) token * ('a,'b) token -> bool
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end
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(* LR_PARSER: signature for a polymorphic LR parser *)
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signature LR_PARSER =
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sig
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structure Stream: STREAM
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structure LrTable : LR_TABLE
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structure Token : TOKEN
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sharing LrTable = Token.LrTable
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exception ParseError
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val parse : {table : LrTable.table,
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lexer : ('_b,'_c) Token.token Stream.stream,
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arg: 'arg,
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saction : int *
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'_c *
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(LrTable.state * ('_b * '_c * '_c)) list *
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'arg ->
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LrTable.nonterm *
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('_b * '_c * '_c) *
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((LrTable.state *('_b * '_c * '_c)) list),
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void : '_b,
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ec : { is_keyword : LrTable.term -> bool,
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noShift : LrTable.term -> bool,
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preferred_change : (LrTable.term list * LrTable.term list) list,
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errtermvalue : LrTable.term -> '_b,
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showTerminal : LrTable.term -> string,
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terms: LrTable.term list,
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error : string * '_c * '_c -> unit
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},
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lookahead : int (* max amount of lookahead used in *)
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(* error correction *)
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} -> '_b *
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(('_b,'_c) Token.token Stream.stream)
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end
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(* LEXER: a signature that most lexers produced for use with SML-Yacc's
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output will match. The user is responsible for declaring type token,
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type pos, and type svalue in the UserDeclarations section of a lexer.
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Note that type token is abstract in the lexer. This allows SML-Yacc to
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create a TOKENS signature for use with lexers produced by ML-Lex that
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treats the type token abstractly. Lexers that are functors parametrized by
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a Tokens structure matching a TOKENS signature cannot examine the structure
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of tokens.
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*)
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signature LEXER =
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sig
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structure UserDeclarations :
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sig
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type ('a,'b) token
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type pos
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type svalue
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end
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val makeLexer : (int -> string) -> unit ->
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(UserDeclarations.svalue,UserDeclarations.pos) UserDeclarations.token
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end
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(* ARG_LEXER: the %arg option of ML-Lex allows users to produce lexers which
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also take an argument before yielding a function from unit to a token
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*)
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signature ARG_LEXER =
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sig
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structure UserDeclarations :
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sig
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type ('a,'b) token
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type pos
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type svalue
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type arg
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end
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val makeLexer : (int -> string) -> UserDeclarations.arg -> unit ->
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(UserDeclarations.svalue,UserDeclarations.pos) UserDeclarations.token
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end
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(* PARSER_DATA: the signature of ParserData structures in {parser name}LrValsFun
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produced by SML-Yacc. All such structures match this signature.
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The {parser name}LrValsFun produces a structure which contains all the values
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except for the lexer needed to call the polymorphic parser mentioned
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before.
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*)
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signature PARSER_DATA =
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sig
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(* the type of line numbers *)
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type pos
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(* the type of semantic values *)
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type svalue
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(* the type of the user-supplied argument to the parser *)
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type arg
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(* the intended type of the result of the parser. This value is
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produced by applying extract from the structure Actions to the
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final semantic value resultiing from a parse.
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*)
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type result
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structure LrTable : LR_TABLE
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structure Token : TOKEN
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sharing Token.LrTable = LrTable
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(* structure Actions contains the functions which mantain the
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semantic values stack in the parser. Void is used to provide
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a default value for the semantic stack.
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*)
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structure Actions :
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sig
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val actions : int * pos *
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(LrTable.state * (svalue * pos * pos)) list * arg->
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LrTable.nonterm * (svalue * pos * pos) *
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((LrTable.state *(svalue * pos * pos)) list)
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val void : svalue
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val extract : svalue -> result
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end
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(* structure EC contains information used to improve error
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recovery in an error-correcting parser *)
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structure EC :
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sig
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val is_keyword : LrTable.term -> bool
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val noShift : LrTable.term -> bool
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val preferred_change : (LrTable.term list * LrTable.term list) list
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val errtermvalue : LrTable.term -> svalue
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val showTerminal : LrTable.term -> string
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val terms: LrTable.term list
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end
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(* table is the LR table for the parser *)
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val table : LrTable.table
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end
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(* signature PARSER is the signature that most user parsers created by
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SML-Yacc will match.
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*)
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signature PARSER =
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sig
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structure Token : TOKEN
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structure Stream : STREAM
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exception ParseError
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(* type pos is the type of line numbers *)
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type pos
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(* type result is the type of the result from the parser *)
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type result
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(* the type of the user-supplied argument to the parser *)
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type arg
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(* type svalue is the type of semantic values for the semantic value
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stack
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*)
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type svalue
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(* val makeLexer is used to create a stream of tokens for the parser *)
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val makeLexer : (int -> string) ->
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(svalue,pos) Token.token Stream.stream
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(* val parse takes a stream of tokens and a function to TextIO.print
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errors and returns a value of type result and a stream containing
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the unused tokens
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*)
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val parse : int * ((svalue,pos) Token.token Stream.stream) *
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(string * pos * pos -> unit) * arg ->
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result * (svalue,pos) Token.token Stream.stream
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val sameToken : (svalue,pos) Token.token * (svalue,pos) Token.token ->
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bool
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end
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(* signature ARG_PARSER is the signature that will be matched by parsers whose
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lexer takes an additional argument.
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*)
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signature ARG_PARSER =
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sig
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structure Token : TOKEN
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structure Stream : STREAM
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exception ParseError
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type arg
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type lexarg
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type pos
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type result
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type svalue
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val makeLexer : (int -> string) -> lexarg ->
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(svalue,pos) Token.token Stream.stream
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val parse : int * ((svalue,pos) Token.token Stream.stream) *
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(string * pos * pos -> unit) * arg ->
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result * (svalue,pos) Token.token Stream.stream
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val sameToken : (svalue,pos) Token.token * (svalue,pos) Token.token ->
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bool
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end
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(**** Original file: join.sml ****)
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(* ML-Yacc Parser Generator (c) 1989 Andrew W. Appel, David R. Tarditi *)
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(* functor Join creates a user parser by putting together a Lexer structure,
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an LrValues structure, and a polymorphic parser structure. Note that
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the Lexer and LrValues structure must share the type pos (i.e. the type
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of line numbers), the type svalues for semantic values, and the type
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of tokens.
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*)
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functor Join(structure Lex : LEXER
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structure ParserData: PARSER_DATA
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structure LrParser : LR_PARSER
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sharing ParserData.LrTable = LrParser.LrTable
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sharing ParserData.Token = LrParser.Token
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sharing type Lex.UserDeclarations.svalue = ParserData.svalue
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sharing type Lex.UserDeclarations.pos = ParserData.pos
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sharing type Lex.UserDeclarations.token = ParserData.Token.token)
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: PARSER =
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struct
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structure Token = ParserData.Token
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structure Stream = LrParser.Stream
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exception ParseError = LrParser.ParseError
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type arg = ParserData.arg
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type pos = ParserData.pos
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type result = ParserData.result
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type svalue = ParserData.svalue
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val makeLexer = LrParser.Stream.streamify o Lex.makeLexer
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val parse = fn (lookahead,lexer,error,arg) =>
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(fn (a,b) => (ParserData.Actions.extract a,b))
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(LrParser.parse {table = ParserData.table,
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lexer=lexer,
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lookahead=lookahead,
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saction = ParserData.Actions.actions,
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arg=arg,
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void= ParserData.Actions.void,
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ec = {is_keyword = ParserData.EC.is_keyword,
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noShift = ParserData.EC.noShift,
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preferred_change = ParserData.EC.preferred_change,
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errtermvalue = ParserData.EC.errtermvalue,
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error=error,
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showTerminal = ParserData.EC.showTerminal,
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terms = ParserData.EC.terms}}
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)
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val sameToken = Token.sameToken
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end
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(* functor JoinWithArg creates a variant of the parser structure produced
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above. In this case, the makeLexer take an additional argument before
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yielding a value of type unit -> (svalue,pos) token
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*)
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functor JoinWithArg(structure Lex : ARG_LEXER
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structure ParserData: PARSER_DATA
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structure LrParser : LR_PARSER
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sharing ParserData.LrTable = LrParser.LrTable
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sharing ParserData.Token = LrParser.Token
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sharing type Lex.UserDeclarations.svalue = ParserData.svalue
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sharing type Lex.UserDeclarations.pos = ParserData.pos
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sharing type Lex.UserDeclarations.token = ParserData.Token.token)
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: ARG_PARSER =
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struct
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structure Token = ParserData.Token
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structure Stream = LrParser.Stream
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exception ParseError = LrParser.ParseError
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type arg = ParserData.arg
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type lexarg = Lex.UserDeclarations.arg
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type pos = ParserData.pos
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type result = ParserData.result
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type svalue = ParserData.svalue
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val makeLexer = fn s => fn arg =>
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LrParser.Stream.streamify (Lex.makeLexer s arg)
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val parse = fn (lookahead,lexer,error,arg) =>
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(fn (a,b) => (ParserData.Actions.extract a,b))
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(LrParser.parse {table = ParserData.table,
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lexer=lexer,
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lookahead=lookahead,
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saction = ParserData.Actions.actions,
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arg=arg,
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void= ParserData.Actions.void,
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|
424 |
ec = {is_keyword = ParserData.EC.is_keyword,
|
|
425 |
noShift = ParserData.EC.noShift,
|
|
426 |
preferred_change = ParserData.EC.preferred_change,
|
|
427 |
errtermvalue = ParserData.EC.errtermvalue,
|
|
428 |
error=error,
|
|
429 |
showTerminal = ParserData.EC.showTerminal,
|
|
430 |
terms = ParserData.EC.terms}}
|
|
431 |
)
|
|
432 |
val sameToken = Token.sameToken
|
|
433 |
end;
|
|
434 |
|
|
435 |
(**** Original file: lrtable.sml ****)
|
|
436 |
|
|
437 |
(* ML-Yacc Parser Generator (c) 1989 Andrew W. Appel, David R. Tarditi *)
|
|
438 |
structure LrTable : LR_TABLE =
|
|
439 |
struct
|
|
440 |
open Array List
|
|
441 |
infix 9 sub
|
|
442 |
datatype ('a,'b) pairlist = EMPTY
|
|
443 |
| PAIR of 'a * 'b * ('a,'b) pairlist
|
|
444 |
datatype term = T of int
|
|
445 |
datatype nonterm = NT of int
|
|
446 |
datatype state = STATE of int
|
|
447 |
datatype action = SHIFT of state
|
|
448 |
| REDUCE of int (* rulenum from grammar *)
|
|
449 |
| ACCEPT
|
|
450 |
| ERROR
|
|
451 |
exception Goto of state * nonterm
|
|
452 |
type table = {states: int, rules : int,initialState: state,
|
|
453 |
action: ((term,action) pairlist * action) array,
|
|
454 |
goto : (nonterm,state) pairlist array}
|
|
455 |
val numStates = fn ({states,...} : table) => states
|
|
456 |
val numRules = fn ({rules,...} : table) => rules
|
|
457 |
val describeActions =
|
|
458 |
fn ({action,...} : table) =>
|
|
459 |
fn (STATE s) => action sub s
|
|
460 |
val describeGoto =
|
|
461 |
fn ({goto,...} : table) =>
|
|
462 |
fn (STATE s) => goto sub s
|
|
463 |
fun findTerm (T term,row,default) =
|
|
464 |
let fun find (PAIR (T key,data,r)) =
|
|
465 |
if key < term then find r
|
|
466 |
else if key=term then data
|
|
467 |
else default
|
|
468 |
| find EMPTY = default
|
|
469 |
in find row
|
|
470 |
end
|
|
471 |
fun findNonterm (NT nt,row) =
|
|
472 |
let fun find (PAIR (NT key,data,r)) =
|
|
473 |
if key < nt then find r
|
|
474 |
else if key=nt then SOME data
|
|
475 |
else NONE
|
|
476 |
| find EMPTY = NONE
|
|
477 |
in find row
|
|
478 |
end
|
|
479 |
val action = fn ({action,...} : table) =>
|
|
480 |
fn (STATE state,term) =>
|
|
481 |
let val (row,default) = action sub state
|
|
482 |
in findTerm(term,row,default)
|
|
483 |
end
|
|
484 |
val goto = fn ({goto,...} : table) =>
|
|
485 |
fn (a as (STATE state,nonterm)) =>
|
|
486 |
case findNonterm(nonterm,goto sub state)
|
|
487 |
of SOME state => state
|
|
488 |
| NONE => raise (Goto a)
|
|
489 |
val initialState = fn ({initialState,...} : table) => initialState
|
|
490 |
val mkLrTable = fn {actions,gotos,initialState,numStates,numRules} =>
|
|
491 |
({action=actions,goto=gotos,
|
|
492 |
states=numStates,
|
|
493 |
rules=numRules,
|
|
494 |
initialState=initialState} : table)
|
|
495 |
end;
|
|
496 |
|
|
497 |
(**** Original file: stream.sml ****)
|
|
498 |
|
|
499 |
(* ML-Yacc Parser Generator (c) 1989 Andrew W. Appel, David R. Tarditi *)
|
|
500 |
|
|
501 |
(* Stream: a structure implementing a lazy stream. The signature STREAM
|
|
502 |
is found in base.sig *)
|
|
503 |
|
|
504 |
structure Stream :> STREAM =
|
|
505 |
struct
|
|
506 |
datatype 'a str = EVAL of 'a * 'a str Unsynchronized.ref | UNEVAL of (unit->'a)
|
|
507 |
|
|
508 |
type 'a stream = 'a str Unsynchronized.ref
|
|
509 |
|
|
510 |
fun get(Unsynchronized.ref(EVAL t)) = t
|
|
511 |
| get(s as Unsynchronized.ref(UNEVAL f)) =
|
|
512 |
let val t = (f(), Unsynchronized.ref(UNEVAL f)) in s := EVAL t; t end
|
|
513 |
|
|
514 |
fun streamify f = Unsynchronized.ref(UNEVAL f)
|
|
515 |
fun cons(a,s) = Unsynchronized.ref(EVAL(a,s))
|
|
516 |
|
|
517 |
end;
|
|
518 |
|
|
519 |
(**** Original file: parser2.sml ****)
|
|
520 |
|
|
521 |
(* ML-Yacc Parser Generator (c) 1989 Andrew W. Appel, David R. Tarditi *)
|
|
522 |
|
|
523 |
(* parser.sml: This is a parser driver for LR tables with an error-recovery
|
|
524 |
routine added to it. The routine used is described in detail in this
|
|
525 |
article:
|
|
526 |
|
|
527 |
'A Practical Method for LR and LL Syntactic Error Diagnosis and
|
|
528 |
Recovery', by M. Burke and G. Fisher, ACM Transactions on
|
|
529 |
Programming Langauges and Systems, Vol. 9, No. 2, April 1987,
|
|
530 |
pp. 164-197.
|
|
531 |
|
|
532 |
This program is an implementation is the partial, deferred method discussed
|
|
533 |
in the article. The algorithm and data structures used in the program
|
|
534 |
are described below.
|
|
535 |
|
|
536 |
This program assumes that all semantic actions are delayed. A semantic
|
|
537 |
action should produce a function from unit -> value instead of producing the
|
|
538 |
normal value. The parser returns the semantic value on the top of the
|
|
539 |
stack when accept is encountered. The user can deconstruct this value
|
|
540 |
and apply the unit -> value function in it to get the answer.
|
|
541 |
|
|
542 |
It also assumes that the lexer is a lazy stream.
|
|
543 |
|
|
544 |
Data Structures:
|
|
545 |
----------------
|
|
546 |
|
|
547 |
* The parser:
|
|
548 |
|
|
549 |
The state stack has the type
|
|
550 |
|
|
551 |
(state * (semantic value * line # * line #)) list
|
|
552 |
|
|
553 |
The parser keeps a queue of (state stack * lexer pair). A lexer pair
|
|
554 |
consists of a terminal * value pair and a lexer. This allows the
|
|
555 |
parser to reconstruct the states for terminals to the left of a
|
|
556 |
syntax error, and attempt to make error corrections there.
|
|
557 |
|
|
558 |
The queue consists of a pair of lists (x,y). New additions to
|
|
559 |
the queue are cons'ed onto y. The first element of x is the top
|
|
560 |
of the queue. If x is nil, then y is reversed and used
|
|
561 |
in place of x.
|
|
562 |
|
|
563 |
Algorithm:
|
|
564 |
----------
|
|
565 |
|
|
566 |
* The steady-state parser:
|
|
567 |
|
|
568 |
This parser keeps the length of the queue of state stacks at
|
|
569 |
a steady state by always removing an element from the front when
|
|
570 |
another element is placed on the end.
|
|
571 |
|
|
572 |
It has these arguments:
|
|
573 |
|
|
574 |
stack: current stack
|
|
575 |
queue: value of the queue
|
|
576 |
lexPair ((terminal,value),lex stream)
|
|
577 |
|
|
578 |
When SHIFT is encountered, the state to shift to and the value are
|
|
579 |
are pushed onto the state stack. The state stack and lexPair are
|
|
580 |
placed on the queue. The front element of the queue is removed.
|
|
581 |
|
|
582 |
When REDUCTION is encountered, the rule is applied to the current
|
|
583 |
stack to yield a triple (nonterm,value,new stack). A new
|
|
584 |
stack is formed by adding (goto(top state of stack,nonterm),value)
|
|
585 |
to the stack.
|
|
586 |
|
|
587 |
When ACCEPT is encountered, the top value from the stack and the
|
|
588 |
lexer are returned.
|
|
589 |
|
|
590 |
When an ERROR is encountered, fixError is called. FixError
|
|
591 |
takes the arguments to the parser, fixes the error if possible and
|
|
592 |
returns a new set of arguments.
|
|
593 |
|
|
594 |
* The distance-parser:
|
|
595 |
|
|
596 |
This parser includes an additional argument distance. It pushes
|
|
597 |
elements on the queue until it has parsed distance tokens, or an
|
|
598 |
ACCEPT or ERROR occurs. It returns a stack, lexer, the number of
|
|
599 |
tokens left unparsed, a queue, and an action option.
|
|
600 |
*)
|
|
601 |
|
|
602 |
signature FIFO =
|
|
603 |
sig type 'a queue
|
|
604 |
val empty : 'a queue
|
|
605 |
exception Empty
|
|
606 |
val get : 'a queue -> 'a * 'a queue
|
|
607 |
val put : 'a * 'a queue -> 'a queue
|
|
608 |
end
|
|
609 |
|
|
610 |
(* drt (12/15/89) -- the functor should be used in development work, but
|
|
611 |
it wastes space in the release version.
|
|
612 |
|
|
613 |
functor ParserGen(structure LrTable : LR_TABLE
|
|
614 |
structure Stream : STREAM) : LR_PARSER =
|
|
615 |
*)
|
|
616 |
|
|
617 |
structure LrParser :> LR_PARSER =
|
|
618 |
struct
|
|
619 |
structure LrTable = LrTable
|
|
620 |
structure Stream = Stream
|
|
621 |
|
|
622 |
fun eqT (LrTable.T i, LrTable.T i') = i = i'
|
|
623 |
|
|
624 |
structure Token : TOKEN =
|
|
625 |
struct
|
|
626 |
structure LrTable = LrTable
|
|
627 |
datatype ('a,'b) token = TOKEN of LrTable.term * ('a * 'b * 'b)
|
|
628 |
val sameToken = fn (TOKEN(t,_),TOKEN(t',_)) => eqT (t,t')
|
|
629 |
end
|
|
630 |
|
|
631 |
open LrTable
|
|
632 |
open Token
|
|
633 |
|
|
634 |
val DEBUG1 = false
|
|
635 |
val DEBUG2 = false
|
|
636 |
exception ParseError
|
|
637 |
exception ParseImpossible of int
|
|
638 |
|
|
639 |
structure Fifo :> FIFO =
|
|
640 |
struct
|
|
641 |
type 'a queue = ('a list * 'a list)
|
|
642 |
val empty = (nil,nil)
|
|
643 |
exception Empty
|
|
644 |
fun get(a::x, y) = (a, (x,y))
|
|
645 |
| get(nil, nil) = raise Empty
|
|
646 |
| get(nil, y) = get(rev y, nil)
|
|
647 |
fun put(a,(x,y)) = (x,a::y)
|
|
648 |
end
|
|
649 |
|
|
650 |
type ('a,'b) elem = (state * ('a * 'b * 'b))
|
|
651 |
type ('a,'b) stack = ('a,'b) elem list
|
|
652 |
type ('a,'b) lexv = ('a,'b) token
|
|
653 |
type ('a,'b) lexpair = ('a,'b) lexv * (('a,'b) lexv Stream.stream)
|
|
654 |
type ('a,'b) distanceParse =
|
|
655 |
('a,'b) lexpair *
|
|
656 |
('a,'b) stack *
|
|
657 |
(('a,'b) stack * ('a,'b) lexpair) Fifo.queue *
|
|
658 |
int ->
|
|
659 |
('a,'b) lexpair *
|
|
660 |
('a,'b) stack *
|
|
661 |
(('a,'b) stack * ('a,'b) lexpair) Fifo.queue *
|
|
662 |
int *
|
|
663 |
action option
|
|
664 |
|
|
665 |
type ('a,'b) ecRecord =
|
|
666 |
{is_keyword : term -> bool,
|
|
667 |
preferred_change : (term list * term list) list,
|
|
668 |
error : string * 'b * 'b -> unit,
|
|
669 |
errtermvalue : term -> 'a,
|
|
670 |
terms : term list,
|
|
671 |
showTerminal : term -> string,
|
|
672 |
noShift : term -> bool}
|
|
673 |
|
|
674 |
local
|
|
675 |
|
|
676 |
val println = fn s => (TextIO.print s; TextIO.print "\n")
|
|
677 |
val showState = fn (STATE s) => "STATE " ^ (Int.toString s)
|
|
678 |
in
|
|
679 |
fun printStack(stack: ('a,'b) stack, n: int) =
|
|
680 |
case stack
|
|
681 |
of (state,_) :: rest =>
|
|
682 |
(TextIO.print("\t" ^ Int.toString n ^ ": ");
|
|
683 |
println(showState state);
|
|
684 |
printStack(rest, n+1))
|
|
685 |
| nil => ()
|
|
686 |
|
|
687 |
fun prAction showTerminal
|
|
688 |
(stack as (state,_) :: _, next as (TOKEN (term,_),_), action) =
|
|
689 |
(println "Parse: state stack:";
|
|
690 |
printStack(stack, 0);
|
|
691 |
TextIO.print(" state="
|
|
692 |
^ showState state
|
|
693 |
^ " next="
|
|
694 |
^ showTerminal term
|
|
695 |
^ " action="
|
|
696 |
);
|
|
697 |
case action
|
|
698 |
of SHIFT state => println ("SHIFT " ^ (showState state))
|
|
699 |
| REDUCE i => println ("REDUCE " ^ (Int.toString i))
|
|
700 |
| ERROR => println "ERROR"
|
|
701 |
| ACCEPT => println "ACCEPT")
|
|
702 |
| prAction _ (_,_,action) = ()
|
|
703 |
end
|
|
704 |
|
|
705 |
(* ssParse: parser which maintains the queue of (state * lexvalues) in a
|
|
706 |
steady-state. It takes a table, showTerminal function, saction
|
|
707 |
function, and fixError function. It parses until an ACCEPT is
|
|
708 |
encountered, or an exception is raised. When an error is encountered,
|
|
709 |
fixError is called with the arguments of parseStep (lexv,stack,and
|
|
710 |
queue). It returns the lexv, and a new stack and queue adjusted so
|
|
711 |
that the lexv can be parsed *)
|
|
712 |
|
|
713 |
val ssParse =
|
|
714 |
fn (table,showTerminal,saction,fixError,arg) =>
|
|
715 |
let val prAction = prAction showTerminal
|
|
716 |
val action = LrTable.action table
|
|
717 |
val goto = LrTable.goto table
|
|
718 |
fun parseStep(args as
|
|
719 |
(lexPair as (TOKEN (terminal, value as (_,leftPos,_)),
|
|
720 |
lexer
|
|
721 |
),
|
|
722 |
stack as (state,_) :: _,
|
|
723 |
queue)) =
|
|
724 |
let val nextAction = action (state,terminal)
|
|
725 |
val _ = if DEBUG1 then prAction(stack,lexPair,nextAction)
|
|
726 |
else ()
|
|
727 |
in case nextAction
|
|
728 |
of SHIFT s =>
|
|
729 |
let val newStack = (s,value) :: stack
|
|
730 |
val newLexPair = Stream.get lexer
|
|
731 |
val (_,newQueue) =Fifo.get(Fifo.put((newStack,newLexPair),
|
|
732 |
queue))
|
|
733 |
in parseStep(newLexPair,(s,value)::stack,newQueue)
|
|
734 |
end
|
|
735 |
| REDUCE i =>
|
|
736 |
(case saction(i,leftPos,stack,arg)
|
|
737 |
of (nonterm,value,stack as (state,_) :: _) =>
|
|
738 |
parseStep(lexPair,(goto(state,nonterm),value)::stack,
|
|
739 |
queue)
|
|
740 |
| _ => raise (ParseImpossible 197))
|
|
741 |
| ERROR => parseStep(fixError args)
|
|
742 |
| ACCEPT =>
|
|
743 |
(case stack
|
|
744 |
of (_,(topvalue,_,_)) :: _ =>
|
|
745 |
let val (token,restLexer) = lexPair
|
|
746 |
in (topvalue,Stream.cons(token,restLexer))
|
|
747 |
end
|
|
748 |
| _ => raise (ParseImpossible 202))
|
|
749 |
end
|
|
750 |
| parseStep _ = raise (ParseImpossible 204)
|
|
751 |
in parseStep
|
|
752 |
end
|
|
753 |
|
|
754 |
(* distanceParse: parse until n tokens are shifted, or accept or
|
|
755 |
error are encountered. Takes a table, showTerminal function, and
|
|
756 |
semantic action function. Returns a parser which takes a lexPair
|
|
757 |
(lex result * lexer), a state stack, a queue, and a distance
|
|
758 |
(must be > 0) to parse. The parser returns a new lex-value, a stack
|
|
759 |
with the nth token shifted on top, a queue, a distance, and action
|
|
760 |
option. *)
|
|
761 |
|
|
762 |
val distanceParse =
|
|
763 |
fn (table,showTerminal,saction,arg) =>
|
|
764 |
let val prAction = prAction showTerminal
|
|
765 |
val action = LrTable.action table
|
|
766 |
val goto = LrTable.goto table
|
|
767 |
fun parseStep(lexPair,stack,queue,0) = (lexPair,stack,queue,0,NONE)
|
|
768 |
| parseStep(lexPair as (TOKEN (terminal, value as (_,leftPos,_)),
|
|
769 |
lexer
|
|
770 |
),
|
|
771 |
stack as (state,_) :: _,
|
|
772 |
queue,distance) =
|
|
773 |
let val nextAction = action(state,terminal)
|
|
774 |
val _ = if DEBUG1 then prAction(stack,lexPair,nextAction)
|
|
775 |
else ()
|
|
776 |
in case nextAction
|
|
777 |
of SHIFT s =>
|
|
778 |
let val newStack = (s,value) :: stack
|
|
779 |
val newLexPair = Stream.get lexer
|
|
780 |
in parseStep(newLexPair,(s,value)::stack,
|
|
781 |
Fifo.put((newStack,newLexPair),queue),distance-1)
|
|
782 |
end
|
|
783 |
| REDUCE i =>
|
|
784 |
(case saction(i,leftPos,stack,arg)
|
|
785 |
of (nonterm,value,stack as (state,_) :: _) =>
|
|
786 |
parseStep(lexPair,(goto(state,nonterm),value)::stack,
|
|
787 |
queue,distance)
|
|
788 |
| _ => raise (ParseImpossible 240))
|
|
789 |
| ERROR => (lexPair,stack,queue,distance,SOME nextAction)
|
|
790 |
| ACCEPT => (lexPair,stack,queue,distance,SOME nextAction)
|
|
791 |
end
|
|
792 |
| parseStep _ = raise (ParseImpossible 242)
|
|
793 |
in parseStep : ('_a,'_b) distanceParse
|
|
794 |
end
|
|
795 |
|
|
796 |
(* mkFixError: function to create fixError function which adjusts parser state
|
|
797 |
so that parse may continue in the presence of an error *)
|
|
798 |
|
|
799 |
fun mkFixError({is_keyword,terms,errtermvalue,
|
|
800 |
preferred_change,noShift,
|
|
801 |
showTerminal,error,...} : ('_a,'_b) ecRecord,
|
|
802 |
distanceParse : ('_a,'_b) distanceParse,
|
|
803 |
minAdvance,maxAdvance)
|
|
804 |
|
|
805 |
(lexv as (TOKEN (term,value as (_,leftPos,_)),_),stack,queue) =
|
|
806 |
let val _ = if DEBUG2 then
|
|
807 |
error("syntax error found at " ^ (showTerminal term),
|
|
808 |
leftPos,leftPos)
|
|
809 |
else ()
|
|
810 |
|
|
811 |
fun tokAt(t,p) = TOKEN(t,(errtermvalue t,p,p))
|
|
812 |
|
|
813 |
val minDelta = 3
|
|
814 |
|
|
815 |
(* pull all the state * lexv elements from the queue *)
|
|
816 |
|
|
817 |
val stateList =
|
|
818 |
let fun f q = let val (elem,newQueue) = Fifo.get q
|
|
819 |
in elem :: (f newQueue)
|
|
820 |
end handle Fifo.Empty => nil
|
|
821 |
in f queue
|
|
822 |
end
|
|
823 |
|
|
824 |
(* now number elements of stateList, giving distance from
|
|
825 |
error token *)
|
|
826 |
|
|
827 |
val (_, numStateList) =
|
|
828 |
List.foldr (fn (a,(num,r)) => (num+1,(a,num)::r)) (0, []) stateList
|
|
829 |
|
|
830 |
(* Represent the set of potential changes as a linked list.
|
|
831 |
|
|
832 |
Values of datatype Change hold information about a potential change.
|
|
833 |
|
|
834 |
oper = oper to be applied
|
|
835 |
pos = the # of the element in stateList that would be altered.
|
|
836 |
distance = the number of tokens beyond the error token which the
|
|
837 |
change allows us to parse.
|
|
838 |
new = new terminal * value pair at that point
|
|
839 |
orig = original terminal * value pair at the point being changed.
|
|
840 |
*)
|
|
841 |
|
|
842 |
datatype ('a,'b) change = CHANGE of
|
|
843 |
{pos : int, distance : int, leftPos: 'b, rightPos: 'b,
|
|
844 |
new : ('a,'b) lexv list, orig : ('a,'b) lexv list}
|
|
845 |
|
|
846 |
|
|
847 |
val showTerms = String.concat o map (fn TOKEN(t,_) => " " ^ showTerminal t)
|
|
848 |
|
|
849 |
val printChange = fn c =>
|
|
850 |
let val CHANGE {distance,new,orig,pos,...} = c
|
|
851 |
in (TextIO.print ("{distance= " ^ (Int.toString distance));
|
|
852 |
TextIO.print (",orig ="); TextIO.print(showTerms orig);
|
|
853 |
TextIO.print (",new ="); TextIO.print(showTerms new);
|
|
854 |
TextIO.print (",pos= " ^ (Int.toString pos));
|
|
855 |
TextIO.print "}\n")
|
|
856 |
end
|
|
857 |
|
|
858 |
val printChangeList = app printChange
|
|
859 |
|
|
860 |
(* parse: given a lexPair, a stack, and the distance from the error
|
|
861 |
token, return the distance past the error token that we are able to parse.*)
|
|
862 |
|
|
863 |
fun parse (lexPair,stack,queuePos : int) =
|
|
864 |
case distanceParse(lexPair,stack,Fifo.empty,queuePos+maxAdvance+1)
|
|
865 |
of (_,_,_,distance,SOME ACCEPT) =>
|
|
866 |
if maxAdvance-distance-1 >= 0
|
|
867 |
then maxAdvance
|
|
868 |
else maxAdvance-distance-1
|
|
869 |
| (_,_,_,distance,_) => maxAdvance - distance - 1
|
|
870 |
|
|
871 |
(* catList: concatenate results of scanning list *)
|
|
872 |
|
|
873 |
fun catList l f = List.foldr (fn(a,r)=> f a @ r) [] l
|
|
874 |
|
|
875 |
fun keywordsDelta new = if List.exists (fn(TOKEN(t,_))=>is_keyword t) new
|
|
876 |
then minDelta else 0
|
|
877 |
|
|
878 |
fun tryChange{lex,stack,pos,leftPos,rightPos,orig,new} =
|
|
879 |
let val lex' = List.foldr (fn (t',p)=>(t',Stream.cons p)) lex new
|
|
880 |
val distance = parse(lex',stack,pos+length new-length orig)
|
|
881 |
in if distance >= minAdvance + keywordsDelta new
|
|
882 |
then [CHANGE{pos=pos,leftPos=leftPos,rightPos=rightPos,
|
|
883 |
distance=distance,orig=orig,new=new}]
|
|
884 |
else []
|
|
885 |
end
|
|
886 |
|
|
887 |
|
|
888 |
(* tryDelete: Try to delete n terminals.
|
|
889 |
Return single-element [success] or nil.
|
|
890 |
Do not delete unshiftable terminals. *)
|
|
891 |
|
|
892 |
|
|
893 |
fun tryDelete n ((stack,lexPair as (TOKEN(term,(_,l,r)),_)),qPos) =
|
|
894 |
let fun del(0,accum,left,right,lexPair) =
|
|
895 |
tryChange{lex=lexPair,stack=stack,
|
|
896 |
pos=qPos,leftPos=left,rightPos=right,
|
|
897 |
orig=rev accum, new=[]}
|
|
898 |
| del(n,accum,left,right,(tok as TOKEN(term,(_,_,r)),lexer)) =
|
|
899 |
if noShift term then []
|
|
900 |
else del(n-1,tok::accum,left,r,Stream.get lexer)
|
|
901 |
in del(n,[],l,r,lexPair)
|
|
902 |
end
|
|
903 |
|
|
904 |
(* tryInsert: try to insert tokens before the current terminal;
|
|
905 |
return a list of the successes *)
|
|
906 |
|
|
907 |
fun tryInsert((stack,lexPair as (TOKEN(_,(_,l,_)),_)),queuePos) =
|
|
908 |
catList terms (fn t =>
|
|
909 |
tryChange{lex=lexPair,stack=stack,
|
|
910 |
pos=queuePos,orig=[],new=[tokAt(t,l)],
|
|
911 |
leftPos=l,rightPos=l})
|
|
912 |
|
|
913 |
(* trySubst: try to substitute tokens for the current terminal;
|
|
914 |
return a list of the successes *)
|
|
915 |
|
|
916 |
fun trySubst ((stack,lexPair as (orig as TOKEN (term,(_,l,r)),lexer)),
|
|
917 |
queuePos) =
|
|
918 |
if noShift term then []
|
|
919 |
else
|
|
920 |
catList terms (fn t =>
|
|
921 |
tryChange{lex=Stream.get lexer,stack=stack,
|
|
922 |
pos=queuePos,
|
|
923 |
leftPos=l,rightPos=r,orig=[orig],
|
|
924 |
new=[tokAt(t,r)]})
|
|
925 |
|
|
926 |
(* do_delete(toks,lexPair) tries to delete tokens "toks" from "lexPair".
|
|
927 |
If it succeeds, returns SOME(toks',l,r,lp), where
|
|
928 |
toks' is the actual tokens (with positions and values) deleted,
|
|
929 |
(l,r) are the (leftmost,rightmost) position of toks',
|
|
930 |
lp is what remains of the stream after deletion
|
|
931 |
*)
|
|
932 |
fun do_delete(nil,lp as (TOKEN(_,(_,l,_)),_)) = SOME(nil,l,l,lp)
|
|
933 |
| do_delete([t],(tok as TOKEN(t',(_,l,r)),lp')) =
|
|
934 |
if eqT (t, t')
|
|
935 |
then SOME([tok],l,r,Stream.get lp')
|
|
936 |
else NONE
|
|
937 |
| do_delete(t::rest,(tok as TOKEN(t',(_,l,r)),lp')) =
|
|
938 |
if eqT (t,t')
|
|
939 |
then case do_delete(rest,Stream.get lp')
|
|
940 |
of SOME(deleted,l',r',lp'') =>
|
|
941 |
SOME(tok::deleted,l,r',lp'')
|
|
942 |
| NONE => NONE
|
|
943 |
else NONE
|
|
944 |
|
|
945 |
fun tryPreferred((stack,lexPair),queuePos) =
|
|
946 |
catList preferred_change (fn (delete,insert) =>
|
|
947 |
if List.exists noShift delete then [] (* should give warning at
|
|
948 |
parser-generation time *)
|
|
949 |
else case do_delete(delete,lexPair)
|
|
950 |
of SOME(deleted,l,r,lp) =>
|
|
951 |
tryChange{lex=lp,stack=stack,pos=queuePos,
|
|
952 |
leftPos=l,rightPos=r,orig=deleted,
|
|
953 |
new=map (fn t=>(tokAt(t,r))) insert}
|
|
954 |
| NONE => [])
|
|
955 |
|
|
956 |
val changes = catList numStateList tryPreferred @
|
|
957 |
catList numStateList tryInsert @
|
|
958 |
catList numStateList trySubst @
|
|
959 |
catList numStateList (tryDelete 1) @
|
|
960 |
catList numStateList (tryDelete 2) @
|
|
961 |
catList numStateList (tryDelete 3)
|
|
962 |
|
|
963 |
val findMaxDist = fn l =>
|
|
964 |
List.foldr (fn (CHANGE {distance,...},high) => Int.max(distance,high)) 0 l
|
|
965 |
|
|
966 |
(* maxDist: max distance past error taken that we could parse *)
|
|
967 |
|
|
968 |
val maxDist = findMaxDist changes
|
|
969 |
|
|
970 |
(* remove changes which did not parse maxDist tokens past the error token *)
|
|
971 |
|
|
972 |
val changes = catList changes
|
|
973 |
(fn(c as CHANGE{distance,...}) =>
|
|
974 |
if distance=maxDist then [c] else [])
|
|
975 |
|
|
976 |
in case changes
|
|
977 |
of (l as change :: _) =>
|
|
978 |
let fun print_msg (CHANGE {new,orig,leftPos,rightPos,...}) =
|
|
979 |
let val s =
|
|
980 |
case (orig,new)
|
|
981 |
of (_::_,[]) => "deleting " ^ (showTerms orig)
|
|
982 |
| ([],_::_) => "inserting " ^ (showTerms new)
|
|
983 |
| _ => "replacing " ^ (showTerms orig) ^
|
|
984 |
" with " ^ (showTerms new)
|
|
985 |
in error ("syntax error: " ^ s,leftPos,rightPos)
|
|
986 |
end
|
|
987 |
|
|
988 |
val _ =
|
|
989 |
(if length l > 1 andalso DEBUG2 then
|
|
990 |
(TextIO.print "multiple fixes possible; could fix it by:\n";
|
|
991 |
app print_msg l;
|
|
992 |
TextIO.print "chosen correction:\n")
|
|
993 |
else ();
|
|
994 |
print_msg change)
|
|
995 |
|
|
996 |
(* findNth: find nth queue entry from the error
|
|
997 |
entry. Returns the Nth queue entry and the portion of
|
|
998 |
the queue from the beginning to the nth-1 entry. The
|
|
999 |
error entry is at the end of the queue.
|
|
1000 |
|
|
1001 |
Examples:
|
|
1002 |
|
|
1003 |
queue = a b c d e
|
|
1004 |
findNth 0 = (e,a b c d)
|
|
1005 |
findNth 1 = (d,a b c)
|
|
1006 |
*)
|
|
1007 |
|
|
1008 |
val findNth = fn n =>
|
|
1009 |
let fun f (h::t,0) = (h,rev t)
|
|
1010 |
| f (h::t,n) = f(t,n-1)
|
|
1011 |
| f (nil,_) = let exception FindNth
|
|
1012 |
in raise FindNth
|
|
1013 |
end
|
|
1014 |
in f (rev stateList,n)
|
|
1015 |
end
|
|
1016 |
|
|
1017 |
val CHANGE {pos,orig,new,...} = change
|
|
1018 |
val (last,queueFront) = findNth pos
|
|
1019 |
val (stack,lexPair) = last
|
|
1020 |
|
|
1021 |
val lp1 = List.foldl(fn (_,(_,r)) => Stream.get r) lexPair orig
|
|
1022 |
val lp2 = List.foldr(fn(t,r)=>(t,Stream.cons r)) lp1 new
|
|
1023 |
|
|
1024 |
val restQueue =
|
|
1025 |
Fifo.put((stack,lp2),
|
|
1026 |
List.foldl Fifo.put Fifo.empty queueFront)
|
|
1027 |
|
|
1028 |
val (lexPair,stack,queue,_,_) =
|
|
1029 |
distanceParse(lp2,stack,restQueue,pos)
|
|
1030 |
|
|
1031 |
in (lexPair,stack,queue)
|
|
1032 |
end
|
|
1033 |
| nil => (error("syntax error found at " ^ (showTerminal term),
|
|
1034 |
leftPos,leftPos); raise ParseError)
|
|
1035 |
end
|
|
1036 |
|
|
1037 |
val parse = fn {arg,table,lexer,saction,void,lookahead,
|
|
1038 |
ec=ec as {showTerminal,...} : ('_a,'_b) ecRecord} =>
|
|
1039 |
let val distance = 15 (* defer distance tokens *)
|
|
1040 |
val minAdvance = 1 (* must parse at least 1 token past error *)
|
|
1041 |
val maxAdvance = Int.max(lookahead,0)(* max distance for parse check *)
|
|
1042 |
val lexPair = Stream.get lexer
|
|
1043 |
val (TOKEN (_,(_,leftPos,_)),_) = lexPair
|
|
1044 |
val startStack = [(initialState table,(void,leftPos,leftPos))]
|
|
1045 |
val startQueue = Fifo.put((startStack,lexPair),Fifo.empty)
|
|
1046 |
val distanceParse = distanceParse(table,showTerminal,saction,arg)
|
|
1047 |
val fixError = mkFixError(ec,distanceParse,minAdvance,maxAdvance)
|
|
1048 |
val ssParse = ssParse(table,showTerminal,saction,fixError,arg)
|
|
1049 |
fun loop (lexPair,stack,queue,_,SOME ACCEPT) =
|
|
1050 |
ssParse(lexPair,stack,queue)
|
|
1051 |
| loop (lexPair,stack,queue,0,_) = ssParse(lexPair,stack,queue)
|
|
1052 |
| loop (lexPair,stack,queue,distance,SOME ERROR) =
|
|
1053 |
let val (lexPair,stack,queue) = fixError(lexPair,stack,queue)
|
|
1054 |
in loop (distanceParse(lexPair,stack,queue,distance))
|
|
1055 |
end
|
|
1056 |
| loop _ = let exception ParseInternal
|
|
1057 |
in raise ParseInternal
|
|
1058 |
end
|
|
1059 |
in loop (distanceParse(lexPair,startStack,startQueue,distance))
|
|
1060 |
end
|
|
1061 |
end;
|
|
1062 |
|
|
1063 |
;
|
|
1064 |
print_depth 10;
|