;;; The contents of this file are subject to the Netscape Public License ;;; Version 1.0 (the "NPL"); you may not use this file except in ;;; compliance with the NPL. You may obtain a copy of the NPL at ;;; http://www.mozilla.org/NPL/ ;;; ;;; Software distributed under the NPL is distributed on an "AS IS" basis, ;;; WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL ;;; for the specific language governing rights and limitations under the ;;; NPL. ;;; ;;; The Initial Developer of this code under the NPL is Netscape ;;; Communications Corporation. Portions created by Netscape are ;;; Copyright (C) 1998 Netscape Communications Corporation. All Rights ;;; Reserved. ;;; ;;; LALR(1) and LR(1) parametrized grammar utilities ;;; ;;; Waldemar Horwat (waldemar@netscape.com) ;;; ;;; ------------------------------------------------------------------------------------------------------ ;;; UTILITIES (declaim (inline identifier?)) (defun identifier? (form) (and form (symbolp form) (not (keywordp form)))) (deftype identifier () '(satisfies identifier?)) ; Make sure that form is one of the following: ; A symbol ; An integer ; A float ; A character ; A string ; A list of zero or more forms that also satisfy ensure-proper-form; ; the list cannot be dotted. ; Return the form. (defun ensure-proper-form (form) (labels ((ensure-list-form (form) (or (null form) (and (consp form) (progn (ensure-proper-form (car form)) (ensure-list-form (cdr form))))))) (unless (or (symbolp form) (integerp form) (floatp form) (characterp form) (stringp form) (ensure-list-form form)) (error "Bad form: ~S" form)) form)) ;;; ------------------------------------------------------------------------------------------------------ ;;; TERMINALS ; A terminal is any of the following: ; A symbol that is neither nil nor a keyword ; A string; ; A character; ; An integer. (defun terminal? (x) (and x (or (and (symbolp x) (not (keywordp x))) (stringp x) (characterp x) (integerp x)))) ; The following terminals are reserved and may not be used in user input: ; $$ Marker for end of token stream (defconstant *end-marker* '$$) (defconstant *end-marker-terminal-number* 0) (deftype terminal () '(satisfies terminal?)) (deftype user-terminal () `(and terminal (not (eql ,*end-marker*)))) ; Emit markup for a terminal. subscript is an optional integer. (defun depict-terminal (markup-stream terminal &optional subscript) (cond ((characterp terminal) (depict-char-style (markup-stream ':character-literal) (depict-character markup-stream terminal) (when subscript (depict-char-style (markup-stream ':plain-subscript) (depict-integer markup-stream subscript))))) ((and terminal (symbolp terminal)) (let ((name (symbol-name terminal))) (if (and (> (length name) 0) (char= (char name 0) #\$)) (depict-char-style (markup-stream ':terminal) (depict markup-stream (subseq (symbol-upper-mixed-case-name terminal) 1)) (when subscript (depict-char-style (markup-stream ':plain-subscript) (depict-integer markup-stream subscript)))) (progn (depict-char-style (markup-stream ':terminal-keyword) (depict markup-stream (string-downcase name))) (when subscript (depict-char-style (markup-stream ':terminal) (depict-char-style (markup-stream ':plain-subscript) (depict-integer markup-stream subscript)))))))) (t (error "Don't know how to emit markup for terminal ~S" terminal)))) ;;; ------------------------------------------------------------------------------------------------------ ;;; NONTERMINAL PARAMETERS (declaim (inline nonterminal-parameter?)) (defun nonterminal-parameter? (x) (symbolp x)) (deftype nonterminal-parameter () 'symbol) ; Return true if this nonterminal parameter is a constant. (declaim (inline nonterminal-attribute?)) (defun nonterminal-attribute? (parameter) (and (symbolp parameter) (not (keywordp parameter)))) (deftype nonterminal-attribute () '(and symbol (not keyword))) (defun depict-nonterminal-attribute (markup-stream attribute) (depict-char-style (markup-stream ':nonterminal) (depict-char-style (markup-stream ':nonterminal-attribute) (depict markup-stream (symbol-lower-mixed-case-name attribute))))) ; Return true if this nonterminal parameter is a variable. (declaim (inline nonterminal-argument?)) (defun nonterminal-argument? (parameter) (keywordp parameter)) (deftype nonterminal-argument () 'keyword) (defparameter *special-nonterminal-arguments* '(:alpha :beta :gamma :delta :epsilon :zeta :eta :theta :iota :kappa :lambda :mu :nu :xi :omicron :pi :rho :sigma :tau :upsilon :phi :chi :psi :omega)) (defun depict-nonterminal-argument-symbol (markup-stream argument) (depict-char-style (markup-stream ':nonterminal-argument) (let ((argument (symbol-abbreviation argument))) (depict markup-stream (if (member argument *special-nonterminal-arguments*) argument (symbol-upper-mixed-case-name argument)))))) (defun depict-nonterminal-argument (markup-stream argument) (depict-char-style (markup-stream ':nonterminal) (depict-nonterminal-argument-symbol markup-stream argument))) ;;; ------------------------------------------------------------------------------------------------------ ;;; ATTRIBUTED NONTERMINALS ; An attributed-nonterminal is a specific instantiation of a generic-nonterminal. (defstruct (attributed-nonterminal (:constructor allocate-attributed-nonterminal (symbol attributes)) (:copier nil) (:predicate attributed-nonterminal?)) (symbol nil :type keyword :read-only t) ;The name of the attributed nonterminal (attributes nil :type list :read-only t)) ;Ordered list of nonterminal attributes ; Make an attributed nonterminal with the given symbol and attributes. If there ; are no attributes, return the symbol as a plain nonterminal. ; Nonterminals are eq whenever they have identical symbols and attribute lists. (defun make-attributed-nonterminal (symbol attributes) (assert-type symbol keyword) (assert-type attributes (list nonterminal-attribute)) (if attributes (let ((generic-nonterminals (get symbol 'generic-nonterminals))) (or (cdr (assoc attributes generic-nonterminals :test #'equal)) (let ((attributed-nonterminal (allocate-attributed-nonterminal symbol attributes))) (setf (get symbol 'generic-nonterminals) (acons attributes attributed-nonterminal generic-nonterminals)) attributed-nonterminal))) symbol)) (defmethod print-object ((attributed-nonterminal attributed-nonterminal) stream) (print-unreadable-object (attributed-nonterminal stream) (format stream "a ~@_~W~{ ~:_~W~}" (attributed-nonterminal-symbol attributed-nonterminal) (attributed-nonterminal-attributes attributed-nonterminal)))) ;;; ------------------------------------------------------------------------------------------------------ ;;; GENERIC NONTERMINALS ; A generic-nonterminal is a parametrized nonterminal that can expand into two or more ; attributed-nonterminals. (defstruct (generic-nonterminal (:constructor allocate-generic-nonterminal (symbol parameters)) (:copier nil) (:predicate generic-nonterminal?)) (symbol nil :type keyword :read-only t) ;The name of the generic nonterminal (parameters nil :type list :read-only t)) ;Ordered list of nonterminal attributes or arguments ; Make a generic nonterminal with the given symbol and parameters. If none of ; the parameters is an argument, make an attributed nonterminal instead. If there ; are no parameters, return the symbol as a plain nonterminal. ; Nonterminals are eq whenever they have identical symbols and parameter lists. (defun make-generic-nonterminal (symbol parameters) (assert-type symbol keyword) (if parameters (let ((generic-nonterminals (get symbol 'generic-nonterminals))) (or (cdr (assoc parameters generic-nonterminals :test #'equal)) (progn (assert-type parameters (list nonterminal-parameter)) (let ((generic-nonterminal (if (every #'nonterminal-attribute? parameters) (allocate-attributed-nonterminal symbol parameters) (allocate-generic-nonterminal symbol parameters)))) (setf (get symbol 'generic-nonterminals) (acons parameters generic-nonterminal generic-nonterminals)) generic-nonterminal)))) symbol)) (defmethod print-object ((generic-nonterminal generic-nonterminal) stream) (print-unreadable-object (generic-nonterminal stream) (format stream "g ~@_~W~{ ~:_~W~}" (generic-nonterminal-symbol generic-nonterminal) (generic-nonterminal-parameters generic-nonterminal)))) ;;; ------------------------------------------------------------------------------------------------------ ;;; NONTERMINALS ;;; A nonterminal is a keyword or an attributed-nonterminal. (declaim (inline nonterminal?)) (defun nonterminal? (x) (or (keywordp x) (attributed-nonterminal? x))) ; The following nonterminals are reserved and may not be used in user input: ; :% Nonterminal that expands to the start nonterminal (defconstant *start-nonterminal* :%) (deftype nonterminal () '(or keyword attributed-nonterminal)) (deftype user-nonterminal () `(and nonterminal (not (eql ,*start-nonterminal*)))) ;;; ------------------------------------------------------------------------------------------------------ ;;; GENERAL NONTERMINALS ;;; A general-nonterminal is a nonterminal or a generic-nonterminal. (declaim (inline general-nonterminal?)) (defun general-nonterminal? (x) (or (nonterminal? x) (generic-nonterminal? x))) (deftype general-nonterminal () '(or nonterminal generic-nonterminal)) ; Return the list of parameters in the general-nonterminal. The list is empty if the ; general-nonterminal is a plain nonterminal. (defun general-nonterminal-parameters (general-nonterminal) (cond ((attributed-nonterminal? general-nonterminal) (attributed-nonterminal-attributes general-nonterminal)) ((generic-nonterminal? general-nonterminal) (generic-nonterminal-parameters general-nonterminal)) (t (progn (assert-true (keywordp general-nonterminal)) nil)))) ; Emit markup for a general-nonterminal. subscript is an optional integer. ; link should be one of: ; :reference if this is a reference of this general-nonterminal; ; :external if this is an external reference of this general-nonterminal; ; :definition if this is a definition of this general-nonterminal; ; nil if this use of the general-nonterminal should not be cross-referenced. (defun depict-general-nonterminal (markup-stream general-nonterminal link &optional subscript) (labels ((depict-nonterminal-name (markup-stream symbol) (let ((name (symbol-upper-mixed-case-name symbol))) (depict-link (markup-stream link "N-" name t) (depict markup-stream name)))) (depict-nonterminal-parameter (markup-stream parameter) (if (nonterminal-attribute? parameter) (depict-char-style (markup-stream ':nonterminal-attribute) (depict markup-stream (symbol-lower-mixed-case-name parameter))) (depict-nonterminal-argument-symbol markup-stream parameter))) (depict-parametrized-nonterminal (markup-stream symbol parameters) (depict-nonterminal-name markup-stream symbol) (depict-char-style (markup-stream ':superscript) (depict-list markup-stream #'depict-nonterminal-parameter parameters :separator ","))) (depict-general (markup-stream) (depict-char-style (markup-stream ':nonterminal) (cond ((keywordp general-nonterminal) (depict-nonterminal-name markup-stream general-nonterminal)) ((attributed-nonterminal? general-nonterminal) (depict-parametrized-nonterminal markup-stream (attributed-nonterminal-symbol general-nonterminal) (attributed-nonterminal-attributes general-nonterminal))) ((generic-nonterminal? general-nonterminal) (depict-parametrized-nonterminal markup-stream (generic-nonterminal-symbol general-nonterminal) (generic-nonterminal-parameters general-nonterminal))) (t (error "Bad nonterminal ~S" general-nonterminal))) (when subscript (depict-char-style (markup-stream ':plain-subscript) (depict-integer markup-stream subscript)))))) (if (or (eq link :definition) (and (or (eq link :reference) (eq link :external)) (keywordp general-nonterminal) (null subscript))) (depict-link (markup-stream link "N-" (symbol-upper-mixed-case-name (general-grammar-symbol-symbol general-nonterminal)) t) (setq link nil) (depict-general markup-stream)) (depict-general markup-stream)))) ;;; ------------------------------------------------------------------------------------------------------ ;;; GRAMMAR SYMBOLS ;;; A grammar-symbol is either a terminal or a nonterminal. (deftype grammar-symbol () '(or terminal nonterminal)) (deftype user-grammar-symbol () '(or user-terminal user-nonterminal)) ;;; A general-grammar-symbol is either a terminal or a general-nonterminal. (deftype general-grammar-symbol () '(or terminal general-nonterminal)) ; Return true if the two grammar symbols are the same symbol. (declaim (inline grammar-symbol-=)) (defun grammar-symbol-= (grammar-symbol1 grammar-symbol2) (eql grammar-symbol1 grammar-symbol2)) ; A version of grammar-symbol-= suitable for being the test function for hash tables. (defconstant *grammar-symbol-=* #'eql) ; Return the general-grammar-symbol's symbol. Return it unchanged if it is not ; an attributed or generic nonterminal. (defun general-grammar-symbol-symbol (general-grammar-symbol) (cond ((attributed-nonterminal? general-grammar-symbol) (attributed-nonterminal-symbol general-grammar-symbol)) ((generic-nonterminal? general-grammar-symbol) (generic-nonterminal-symbol general-grammar-symbol)) (t (assert-type general-grammar-symbol (or keyword terminal))))) ; Return the list of arguments in the general-grammar-symbol. The list is empty if the ; general-grammar-symbol is not a generic nonterminal. (defun general-grammar-symbol-arguments (general-grammar-symbol) (and (generic-nonterminal? general-grammar-symbol) (remove-if (complement #'nonterminal-argument?) (generic-nonterminal-parameters general-grammar-symbol)))) ; Return the general-grammar-symbol expanded into source form that can be interned to yield the same ; general-grammar-symbol. (defun general-grammar-symbol-source (general-grammar-symbol) (cond ((attributed-nonterminal? general-grammar-symbol) (cons (attributed-nonterminal-symbol general-grammar-symbol) (attributed-nonterminal-attributes general-grammar-symbol))) ((generic-nonterminal? general-grammar-symbol) (cons (generic-nonterminal-symbol general-grammar-symbol) (generic-nonterminal-parameters general-grammar-symbol))) (t (assert-type general-grammar-symbol (or keyword terminal))))) ; Emit markup for a general-grammar-symbol. subscript is an optional integer. ; link should be one of: ; :reference if this is a reference of this general-grammar-symbol; ; :external if this is an external reference of this general-grammar-symbol; ; :definition if this is a definition of this general-grammar-symbol; ; nil if this use of the general-grammar-symbol should not be cross-referenced. (defun depict-general-grammar-symbol (markup-stream general-grammar-symbol link &optional subscript) (if (general-nonterminal? general-grammar-symbol) (depict-general-nonterminal markup-stream general-grammar-symbol link subscript) (depict-terminal markup-stream general-grammar-symbol subscript))) ; Styled text can include (:grammar-symbol []) as long as ; *styled-text-grammar-parametrization* is bound around the call to depict-styled-text. (defvar *styled-text-grammar-parametrization*) (defun depict-grammar-symbol-styled-text (markup-stream grammar-symbol-source &optional subscript) (depict-general-grammar-symbol markup-stream (grammar-parametrization-intern *styled-text-grammar-parametrization* grammar-symbol-source) :reference subscript)) (setf (styled-text-depictor :grammar-symbol) #'depict-grammar-symbol-styled-text) ;;; ------------------------------------------------------------------------------------------------------ ;;; GRAMMAR PARAMETRIZATIONS ; A grammar parametrization holds the rules for converting nonterminal arguments into nonterminal attributes. (defstruct (grammar-parametrization (:constructor allocate-grammar-parametrization (argument-attributes)) (:predicate grammar-parametrization?)) (argument-attributes nil :type hash-table :read-only t)) ;Hash table of nonterminal-argument -> list of nonterminal-attributes (defun make-grammar-parametrization () (allocate-grammar-parametrization (make-hash-table :test #'eq))) ; Declare that nonterminal arguments with the given name can hold any of the ; given nonterminal attributes given. At least one attribute must be provided. (defun grammar-parametrization-declare-argument (grammar-parametrization argument attributes) (assert-type argument nonterminal-argument) (assert-type attributes (list nonterminal-attribute)) (assert-true attributes) (when (gethash argument (grammar-parametrization-argument-attributes grammar-parametrization)) (error "Duplicate parametrized grammar argument ~S" argument)) (setf (gethash argument (grammar-parametrization-argument-attributes grammar-parametrization)) attributes)) ; Return the attributes to which the given argument may expand. (defun grammar-parametrization-lookup-argument (grammar-parametrization argument) (assert-non-null (gethash argument (grammar-parametrization-argument-attributes grammar-parametrization)))) ; Create a plain, attributed, or generic grammar symbol from the specification in grammar-symbol-source. ; If grammar-symbol-source is not a cons, it is a plain grammar symbol. If it is a list, its first element ; must be a keyword that is a nonterminal's symbol and the other elements must be nonterminal ; parameters. ; Return two values: ; the grammar symbol ; a list of arguments used in the grammar symbol. ; If allowed-arguments is given, check that each argument is in the allowed-arguments list; ; if not, allow any arguments declared in grammar-parametrization but do not allow duplicates. (defun grammar-parametrization-intern (grammar-parametrization grammar-symbol-source &optional (allowed-arguments nil allow-duplicates)) (if (consp grammar-symbol-source) (progn (assert-type grammar-symbol-source (cons keyword (list nonterminal-parameter))) (let* ((symbol (car grammar-symbol-source)) (parameters (cdr grammar-symbol-source)) (arguments (remove-if (complement #'nonterminal-argument?) parameters))) (mapl #'(lambda (arguments) (let ((argument (car arguments))) (if allow-duplicates (unless (member argument allowed-arguments :test #'eq) (error "Undefined nonterminal argument ~S" argument)) (progn (unless (gethash argument (grammar-parametrization-argument-attributes grammar-parametrization)) (error "Undeclared nonterminal argument ~S" argument)) (when (member argument (cdr arguments) :test #'eq) (error "Duplicate nonterminal argument ~S" argument)))))) arguments) (values (make-generic-nonterminal symbol parameters) arguments))) (values (assert-type grammar-symbol-source (or keyword terminal)) nil))) ; Call f on each possible binding permutation of the given arguments concatenated with the bindings in ; bound-argument-alist. f takes one argument, an association list that maps arguments to attributes. (defun grammar-parametrization-each-permutation (grammar-parametrization f arguments &optional bound-argument-alist) (if arguments (let ((argument (car arguments)) (rest-arguments (cdr arguments))) (dolist (attribute (grammar-parametrization-lookup-argument grammar-parametrization argument)) (grammar-parametrization-each-permutation grammar-parametrization f rest-arguments (acons argument attribute bound-argument-alist)))) (funcall f bound-argument-alist))) ; If general-grammar-symbol is a generic-nonterminal, return one possible binding permutation of its arguments; ; otherwise return nil. (defun nonterminal-sample-bound-argument-alist (grammar-parametrization general-grammar-symbol) (when (generic-nonterminal? general-grammar-symbol) (grammar-parametrization-each-permutation grammar-parametrization #'(lambda (bound-argument-alist) (return-from nonterminal-sample-bound-argument-alist bound-argument-alist)) (general-grammar-symbol-arguments general-grammar-symbol)))) ; If the grammar symbol is a generic nonterminal, convert it into an attributed nonterminal ; by instantiating its arguments with the corresponding attributes from the bound-argument-alist. ; If the grammar symbol is already an attributed or plain nonterminal, return it unchanged. (defun instantiate-general-grammar-symbol (bound-argument-alist general-grammar-symbol) (if (generic-nonterminal? general-grammar-symbol) (make-attributed-nonterminal (generic-nonterminal-symbol general-grammar-symbol) (mapcar #'(lambda (parameter) (if (nonterminal-argument? parameter) (let ((binding (assoc parameter bound-argument-alist :test #'eq))) (if binding (cdr binding) (error "Unbound nonterminal argument ~S" parameter))) parameter)) (generic-nonterminal-parameters general-grammar-symbol))) (assert-type general-grammar-symbol grammar-symbol))) ; If the grammar symbol is a generic nonterminal parametrized on argument, substitute ; attribute for argument in it and return the modified grammar symbol. Otherwise, return it unchanged. (defun general-grammar-symbol-substitute (attribute argument general-grammar-symbol) (assert-type attribute nonterminal-attribute) (assert-type argument nonterminal-argument) (if (and (generic-nonterminal? general-grammar-symbol) (member argument (generic-nonterminal-parameters general-grammar-symbol) :test #'eq)) (make-generic-nonterminal (generic-nonterminal-symbol general-grammar-symbol) (substitute attribute argument (generic-nonterminal-parameters general-grammar-symbol) :test #'eq)) (assert-type general-grammar-symbol general-grammar-symbol))) ; If the general grammar symbol is a generic nonterminal, return a list of all possible attributed nonterminals ; that can be instantiated from it; otherwise, return a one-element list containing the given general grammar symbol. (defun general-grammar-symbol-instances (grammar-parametrization general-grammar-symbol) (if (generic-nonterminal? general-grammar-symbol) (let ((instances nil)) (grammar-parametrization-each-permutation grammar-parametrization #'(lambda (bound-argument-alist) (push (instantiate-general-grammar-symbol bound-argument-alist general-grammar-symbol) instances)) (general-grammar-symbol-arguments general-grammar-symbol)) (nreverse instances)) (list (assert-type general-grammar-symbol grammar-symbol)))) ; Return true if grammar-symbol can be obtained by calling instantiate-general-grammar-symbol on ; general-grammar-symbol. (defun general-nonterminal-is-instance? (grammar-parametrization general-grammar-symbol grammar-symbol) (or (grammar-symbol-= general-grammar-symbol grammar-symbol) (and (generic-nonterminal? general-grammar-symbol) (attributed-nonterminal? grammar-symbol) (let ((parameters (generic-nonterminal-parameters general-grammar-symbol)) (attributes (attributed-nonterminal-attributes grammar-symbol))) (and (= (length parameters) (length attributes)) (every #'(lambda (parameter attribute) (or (eq parameter attribute) (and (nonterminal-argument? parameter) (member attribute (grammar-parametrization-lookup-argument grammar-parametrization parameter) :test #'eq)))) parameters attributes))))))