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// Copyright (C) 2010-2013, Gabriel Dos Reis.
// All rights reserved.
// Written by Gabriel Dos Reis.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// - Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// - Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in
// the documentation and/or other materials provided with the
// distribution.
//
// - Neither the name of The Numerical Algorithms Group Ltd. nor the
// names of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef OPENAXIOM_SEXPR_INCLUDED
#define OPENAXIOM_SEXPR_INCLUDED
// --% Author: Gabriel Dos Reis.
// --% Description:
// --% A simple support for s-expressions. By design, no ambition
// --% for full-fledged Common Lisp reader capability. Rather,
// --% the aim is a simple data structure for exchanging data
// --% between several components of the OpenAxiom system.
// --% Users interested in fullblown Lisp syntax should seek
// --% to acquire Lisp systems, many of which are freely available.
#include <iosfwd>
#include <vector>
#include <set>
#include <open-axiom/string-pool>
#include <open-axiom/token>
namespace OpenAxiom {
namespace Sexpr {
struct BasicError {
explicit BasicError(const std::string& s) : msg(s) { }
const std::string& message() const { return msg; }
protected:
std::string msg;
};
// -----------
// -- Token --
// -----------
struct Token {
enum Type {
unknown, // unidentified token
semicolon = token::value(";"), // comment
dot = token::value("."),
comma = token::value(","),
open_paren = token::value("("),
close_paren = token::value(")"),
apostrophe = token::value("'"),
backquote = token::value("`"),
backslash = token::value("\\"),
sharp_open_paren = token::value("#("),
sharp_apostrophe = token::value("#'"),
sharp_colon = token::value("#:"),
sharp_plus = token::value("#+"),
sharp_minus = token::value("#-"),
sharp_dot = token::value("#."),
comma_at = token::value(",@"),
digraph_end = token::value(0xff,0xff),
integer, // integer literal
character, // character literal
string, // string literal
identifier, // plain identifier
sharp_integer_equal, // anchor definition, #n=<form>
sharp_integer_sharp // back reference, #n#
};
Type type; // class of this token
BasicString lexeme; // characters making up this token
};
// Print a token object on an output stream.
// Note: this function is for debugging purpose; in particular
// it does not `prettyprint' tokens.
std::ostream& operator<<(std::ostream&, const Token&);
// -----------
// -- Lexer --
// -----------
// An object of this type transforms a sequence of characters
// into a sequence of tokens as defined above.
// A lexer does not manage memory itself. Rather, it delegates
// storage allocation for lexemes and tokens to specialized
// agents used to construct it.
struct Lexer {
Lexer(StringPool& pool, std::vector<Token>& toks)
: strings(pool), tokens(toks) { }
const Byte* tokenize(const Byte*, const Byte*);
BasicString intern(const Byte* s, size_t n) {
return strings.intern(s, n);
}
private:
StringPool& strings; // where to allocate lexemes from
std::vector<Token>& tokens; // where to deposite tokens.
};
// ------------
// -- Syntax --
// ------------
// Base class of syntax object classes.
struct Syntax {
struct Visitor; // base class of syntax visitors
virtual void accept(Visitor&) const = 0;
};
// ----------
// -- Atom --
// ----------
// An atom is a syntax object consisting of exatly one token.
// This should not be confused with the notion of atom
// in Lisp languages.
struct Atom : Syntax {
const Token& token() const { return tok; }
BasicString lexeme() const { return tok.lexeme; }
void accept(Visitor&) const;
protected:
const Token tok;
Atom(const Token&);
};
// -------------
// -- Integer --
// -------------
// Integer literal syntax objects
struct Integer : Atom {
explicit Integer(const Token&);
void accept(Visitor&) const;
};
// ---------------
// -- Character --
// ---------------
// Character literal syntax objects.
struct Character : Atom {
explicit Character(const Token&);
void accept(Visitor&) const;
};
// ------------
// -- String --
// ------------
// Striing literal syntax objjects.
struct String : Atom {
explicit String(const Token&);
void accept(Visitor&) const;
};
// ------------
// -- Symbol --
// ------------
struct Symbol : Atom {
enum Kind {
uninterned, // uninterned symbol
ordinary, // an interned symbol
keyword // a keyword symbol
};
Symbol(const Token&, Kind);
Kind kin() const { return sort; }
void accept(Visitor&) const;
private:
const Kind sort;
};
// ---------------
// -- Reference --
// ---------------
// Back reference object to a syntax object.
struct Reference : Atom {
Reference(const Token&, size_t);
size_t tag() const { return pos; }
void accept(Visitor&) const;
private:
const size_t pos;
};
// ------------
// -- Anchor --
// ------------
// Base anchor syntax object.
struct Anchor : Syntax {
Anchor(size_t, const Syntax*);
size_t ref() const { return tag; }
const Syntax* value() const { return val; }
void accept(Visitor&) const;
private:
const size_t tag;
const Syntax* const val;
};
// -- Abstract over common implementation of unary special operators.
template<typename T>
struct unary_form : Syntax {
const Syntax* body() const { return form; }
void accept(Visitor&) const;
protected:
unary_form(const Syntax* f) : form(f) { }
private:
const Syntax* const form;
};
// -----------
// -- Quote --
// -----------
// Quotation syntax object.
struct Quote : unary_form<Quote> {
explicit Quote(const Syntax*);
};
// ---------------
// -- Antiquote --
// ---------------
// Quasi-quotation syntax object.
struct Antiquote : unary_form<Antiquote> {
explicit Antiquote(const Syntax*);
};
// ------------
// -- Expand --
// ------------
// Expansion request inside a quasi-quotation.
struct Expand : unary_form<Expand> {
explicit Expand(const Syntax*);
};
// ----------
// -- Eval --
// ----------
// Read-time evaluation request syntax object.
struct Eval : unary_form<Eval> {
explicit Eval(const Syntax*);
};
// ------------
// -- Splice --
// ------------
// Splice request syntax object inside a quasi-quotation.
struct Splice : unary_form<Splice> {
explicit Splice(const Syntax*);
};
// --------------
// -- Function --
// --------------
// Function literal syntax object.
struct Function : unary_form<Function> {
explicit Function(const Syntax*);
};
// -------------
// -- DotTail --
// -------------
// Objects of this type represents the tail of syntactic
// objects denoting dotted pair syntax `(a . b)'.
struct DotTail : unary_form<DotTail> {
explicit DotTail(const Syntax*);
};
// -------------
// -- Include --
// -------------
// Conditional inclusion syntax object
struct Include : unary_form<Include> {
explicit Include(const Syntax*);
};
// -------------
// -- Exclude --
// -------------
// Conditional exclusion syntax object
struct Exclude : unary_form<Exclude> {
explicit Exclude(const Syntax*);
};
// ----------
// -- List --
// ----------
// List syntax objects.
struct List : Syntax, private std::vector<const Syntax*> {
typedef std::vector<const Syntax*> base;
using base::const_iterator;
using base::begin;
using base::end;
using base::size;
using base::empty;
List();
explicit List(const base&);
~List();
void accept(Visitor&) const;
};
// ------------
// -- Vector --
// ------------
// Vector syntax objects.
struct Vector : Syntax, private std::vector<const Syntax*> {
typedef std::vector<const Syntax*> base;
using base::const_iterator;
using base::begin;
using base::end;
using base::size;
using base::operator[];
using base::empty;
Vector();
explicit Vector(const base&);
~Vector();
void accept(Visitor&) const;
};
// ---------------------
// -- Syntax::Visitor --
// ---------------------
struct Syntax::Visitor {
virtual void visit(const Atom&) = 0;
virtual void visit(const Integer&);
virtual void visit(const Character&);
virtual void visit(const String&);
virtual void visit(const Symbol&);
virtual void visit(const Reference&);
virtual void visit(const Anchor&) = 0;
virtual void visit(const Quote&) = 0;
virtual void visit(const Antiquote&) = 0;
virtual void visit(const Expand&) = 0;
virtual void visit(const Eval&) = 0;
virtual void visit(const Splice&) = 0;
virtual void visit(const Function&) = 0;
virtual void visit(const Include&) = 0;
virtual void visit(const Exclude&) = 0;
virtual void visit(const DotTail&) = 0;
virtual void visit(const List&) = 0;
virtual void visit(const Vector&) = 0;
};
template<typename T>
void
unary_form<T>::accept(Visitor& v) const {
v.visit(static_cast<const T&>(*this));
}
// ---------------
// -- Allocator --
// ---------------
// The next two classes are helper classes for the main
// allocation class Allocator. We use std::set as allocator
// that guarantee uuniqueness of atomic syntax object with
// respect to the constituent token. That container needs
// a relational comparator. In an ideal world, this class
// should not exist.
struct SyntaxComparator {
bool operator()(const Atom& lhs, const Atom& rhs) const {
return std::less<BasicString>()(lhs.lexeme(), rhs.lexeme());
}
template<typename T>
bool
operator()(const unary_form<T>& lhs, const unary_form<T>& rhs) const {
return std::less<const void*>()(lhs.body(), rhs.body());
}
bool operator()(const Anchor& lhs, const Anchor& rhs) const {
return std::less<size_t>()(lhs.ref(), rhs.ref());
}
};
template<typename T>
struct UniqueAllocator : std::set<T, SyntaxComparator> {
typedef std::set<T, SyntaxComparator> base;
typedef typename base::const_iterator const_iterator;
template<typename... Args>
const T* allocate(const Args&... args) {
return &*this->insert(T(args...)).first;
}
};
// Allocator of syntax objects.
struct Allocator {
Allocator();
~Allocator();
const Integer* make_integer(const Token&);
const Character* make_character(const Token&);
const String* make_string(const Token&);
const Symbol* make_symbol(const Token&, Symbol::Kind);
const Reference* make_reference(const Token&, size_t);
const Anchor* make_anchor(size_t, const Syntax*);
const Quote* make_quote(const Syntax*);
const Antiquote* make_antiquote(const Syntax*);
const Expand* make_expand(const Syntax*);
const Eval* make_eval(const Syntax*);
const Splice* make_splice(const Syntax*);
const Function* make_function(const Syntax*);
const Include* make_include(const Syntax*);
const Exclude* make_exclude(const Syntax*);
const DotTail* make_dot_tail(const Syntax*);
const List* make_list(const std::vector<const Syntax*>&);
const Vector* make_vector(const std::vector<const Syntax*>&);
private:
UniqueAllocator<Integer> ints;
UniqueAllocator<Character> chars;
UniqueAllocator<String> strs;
UniqueAllocator<Symbol> syms;
UniqueAllocator<Anchor> ancs;
UniqueAllocator<Reference> refs;
UniqueAllocator<Quote> quotes;
UniqueAllocator<Antiquote> antis;
UniqueAllocator<Expand> exps;
UniqueAllocator<Function> funs;
UniqueAllocator<Include> incs;
UniqueAllocator<Exclude> excs;
UniqueAllocator<Eval> evls;
UniqueAllocator<Splice> spls;
UniqueAllocator<DotTail> tails;
Memory::Factory<List> lists;
Memory::Factory<Vector> vectors;
List empty_list;
Vector empty_vector;
};
// ------------
// -- Parser --
// ------------
// An object of this type transforms a sequence of tokens
// into a sequence of syntax objects.
// A parser object does not manage memory itself. Rather, it delegates
// storage allocation for syntax objects to specialized
// agents used to construct it.
struct Parser {
Parser(Allocator&, std::vector<const Syntax*>&);
const Token* parse(const Token*, const Token*);
private:
Allocator& alloc;
std::vector<const Syntax*>& syns;
const Symbol* parse_symbol(const Token*&, const Token*);
const Character* parse_character(const Token*&, const Token*);
const Anchor* parse_anchor(const Token*&, const Token*);
const Reference* parse_reference(const Token*&, const Token*);
const Symbol* parse_uninterned(const Token*&, const Token*);
const Function* parse_function(const Token*&, const Token*);
const Quote* parse_quote(const Token*&, const Token*);
const Antiquote* parse_antiquote(const Token*&, const Token*);
const Include* parse_include(const Token*&, const Token*);
const Exclude* parse_exclude(const Token*&, const Token*);
const Expand* parse_expand(const Token*&, const Token*);
const Eval* parse_eval(const Token*&, const Token*);
const Splice* parse_splice(const Token*&, const Token*);
const Vector* parse_vector(const Token*&, const Token*);
const List* parse_list(const Token*&, const Token*);
const Syntax* parse_syntax(const Token*&, const Token*);
};
// ------------
// -- Module --
// ------------
// Entire s-expression input file.
struct Module : std::vector<const Syntax*> {
explicit Module(const std::string&);
const std::string& name() const { return nm; }
private:
const std::string nm;
StringPool raw_strs;
Allocator allocator;
};
}
}
#endif // OPENAXIOM_SEXPR_INCLUDED
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