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Diffstat (limited to 'src/utils/sexpr.cc')
| -rw-r--r-- | src/utils/sexpr.cc | 641 |
1 files changed, 641 insertions, 0 deletions
diff --git a/src/utils/sexpr.cc b/src/utils/sexpr.cc new file mode 100644 index 00000000..d9d38220 --- /dev/null +++ b/src/utils/sexpr.cc @@ -0,0 +1,641 @@ +// Copyright (C) 2010, Gabriel Dos Reis. +// All rights reserved. +// +// 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. + +// --% Author: Gabriel Dos Reis. + +#include <ctype.h> +#include <iostream> +#include <iterator> +#include "sexpr.H" + +namespace OpenAxiom { + namespace Sexpr { + std::ostream& + operator<<(std::ostream& os, const Token& t) { + switch (t.type) { + case Token::dot: os << "DOT"; break; + case Token::comma: os << "COMMA"; break; + case Token::open_paren: os << "OPEN_PAREN"; break; + case Token::close_paren: os << "CLOSE_PAREN"; break; + case Token::apostrophe: os << "APOSTROPHE"; break; + case Token::backquote: os << "BACKQUOTE"; break; + case Token::backslash: os << "BACKSLASH"; break; + case Token::sharp_open_paren: os << "SHARP_OPEN_PAREN"; break; + case Token::sharp_apostrophe: os << "SHARP_APOSTROPHE"; break; + case Token::sharp_colon: os << "SHARP_COLON"; break; + case Token::integer: os << "INTEGER"; break; + case Token::string: os << "STRING"; break; + case Token::identifier: os << "IDENTIFIER"; break; + case Token::sharp_integer_sharp: + os << "SHARP_INTEGER_SHARP"; break; + case Token::sharp_integer_equal: + os << "SHARP_INTEGER_EQUAL"; break; + default: os << "UNKNOWN"; break; + } + os << '('; + if (t.lexeme != 0) { + os << '"'; + std::copy(t.lexeme->begin(), t.lexeme->end(), + std::ostream_iterator<char>(os)); + os << '"'; + } + else + os << "<missing>"; + return os << ')'; + } + + // Return true if character `c' introduces a blank. + static bool + is_blank(char c) { + return c == ' ' or c == '\t' or c == '\v' + or c == '\n' or c == '\f' or c == '\r'; + } + + // Return true if the character `c' introduces a delimiter. + static bool + is_delimiter(char c) { + return is_blank(c) + or c == '(' or c == ')' or c == '\'' + or c == '`' or c == '\\' or c == '#'; + } + + // Move `cur' past all consecutive blank characters, and + // return the new position. + static const char* + skip_blank(const char*& cur, const char* end) { + while (cur < end and is_blank(*cur)) + ++cur; + return cur; + } + + // Move `cur' until a word boundary is reached. + static const char* + skip_to_word_boundary(const char*& cur, const char* end) { + while (cur < end and not is_delimiter(*cur)) + ++cur; + return cur; + } + + // Move `cur' one-past a non-esacaped character `c'. + // Return true if the character was seen. + static bool + skip_to_nonescaped_char(const char*& cur, const char* end, char c) { + for (; cur < end; ++cur) + if (cur[0] == c and cur[-1] != '\\') { + ++cur; + return true; + } + return false; + } + + // Move `cur' past the closing fence of an absolute identifier. + // Return true if the closing fence was effectively seen. + static inline bool + skip_to_fence(const char*& cur, const char* end) { + return skip_to_nonescaped_char(cur, end, '|'); + } + + // Move `cur' past the closing quote of string literal. + // Return true if the closing fence was effectively seen. + static inline bool + skip_to_quote(const char*& cur, const char* end) { + return skip_to_nonescaped_char(cur, end, '"'); + } + + // Return true if the character `c' be part of a non-absolute + // identifier. + static bool + identifier_part(char c) { + switch (c) { + case '+': case '-': case '*': case '/': case '%': case '^': + case '~': case '@': case '$': case '&': case ':': case '=': + case '<': case '>': case '?': case '!': case '_': + return true; + default: + return isalnum(c); + } + } + + // Return true if the character `c' has a special meaning after + // the sharp character. + static bool + special_after_sharp(char c) { + return c == '(' or c == '\'' or c == ':'; + } + + // Return true if the sequence `[cur, end)' has a prefix that is + // an integer followrd by the equal sign or the sharp sign. + // `cur' is moved along the way. + static bool + only_digits_before_equal_or_shap(const char*& cur, const char* end) { + while (cur < end and isdigit(*cur)) + ++cur; + return cur < end and (*cur == '#' or *cur == '='); + } + + // The token `t' was thought to designate an identifier. + // Reclassify it as an integer if, in fact, its lexeme consists + // entirely of digits. + static void + maybe_reclassify(Token& t) { + const char* cur = t.lexeme->begin(); + const char* end = t.lexeme->end(); + while (cur < end and isdigit(*cur)) + ++cur; + if (cur == end) + t.type = Token::integer; + } + + const char* + Lexer::tokenize(const char* cur, const char* end) { + while (skip_blank(cur, end) < end) { + Token t = { Token::unknown, 0 }; + switch (*cur) { + case '.': case ',': case '(': case ')': + case '\'': case '\\': + t.type = Token::Type(OPENAXIOM_SEXPR_TOKEN1(*cur)); + t.lexeme = strings.intern(cur, 1); + ++cur; + break; + + case '#': { + const char* start = cur; + if (cur + 1 < end and special_after_sharp(cur[1])) { + t.type = Token::Type(OPENAXIOM_SEXPR_TOKEN2(cur[0], cur[1])); + t.lexeme = strings.intern(cur, 2); + cur += 2; + } + else if (only_digits_before_equal_or_shap(++cur, end)) { + t.type = *cur == '#' + ? Token::sharp_integer_sharp + : Token::sharp_integer_equal; + t.lexeme = strings.intern(start, cur - start + 1); + ++cur; + } + else { + skip_to_word_boundary(cur, end); + t.lexeme = strings.intern(start, cur - start); + } + break; + } + + case '|': { + const char* start = cur; + skip_to_fence(++cur, end); + t.type = Token::identifier; + t.lexeme = strings.intern(start, cur - start); + break; + } + + case '"': { + const char* start = cur; + skip_to_quote(++cur, end); + t.type = Token::string; + t.lexeme = strings.intern(start, cur - start); + break; + } + + default: + if (identifier_part(*cur)) { + const char* start = cur; + skip_to_word_boundary(++cur, end); + t.type = Token::identifier; + t.lexeme = strings.intern(start, cur - start); + maybe_reclassify(t); + } + else { + const char* start = cur; + skip_to_word_boundary(++cur, end); + t.lexeme = strings.intern(start, cur - start); + } + break; + } + tokens.push_back(t); + } + return cur; + } + + // ---------- + // -- Atom -- + // ---------- + Atom::Atom(const Token& t) : tok(t) { } + + void + Atom::accept(Visitor& v) const { + v.visit(*this); + } + + // ------------- + // -- Integer -- + // ------------- + Integer::Integer(const Token& t) : Atom(t) { } + + void + Integer::accept(Visitor& v) const { + v.visit(*this); + } + + // ------------ + // -- String -- + // ------------ + String::String(const Token& t) : Atom(t) { } + + void + String::accept(Visitor& v) const { + v.visit(*this); + } + + // ------------ + // -- Symbol -- + // ------------ + Symbol::Symbol(const Token& t, Kind k) : Atom(t), sort(k) { } + + void + Symbol::accept(Visitor& v) const { + v.visit(*this); + } + + // ------------ + // -- Anchor -- + // ------------ + Anchor::Anchor(size_t t, const Syntax* s) : tag(t), val(s) { } + + void + Anchor::accept(Visitor& v) const { + v.visit(*this); + } + + // --------------- + // -- Reference -- + // --------------- + Reference::Reference(const Token& t, size_t v) : Atom(t), pos(v) { } + + void + Reference::accept(Visitor& v) const { + v.visit(*this); + } + + // ----------- + // -- Quote -- + // ----------- + Quote::Quote(const Syntax* s) : form(s) { } + + void + Quote::accept(Visitor& v) const { + v.visit(*this); + } + + // -------------- + // -- Function -- + // -------------- + Function::Function(const Syntax* s) : form(s) { } + + void + Function::accept(Visitor& v) const { + v.visit(*this); + } + + // ---------- + // -- Pair -- + // ---------- + Pair::Pair(const Syntax* f, const Syntax* s) : elts(f, s) { } + + void + Pair::accept(Visitor& v) const { + v.visit(*this); + } + + // ---------- + // -- List -- + // ---------- + List::List() { } + + List::List(const base& elts) : base(elts) { } + + List::~List() { } + + void + List::accept(Visitor& v) const { + v.visit(*this); + } + + // ------------ + // -- Vector -- + // ------------ + Vector::Vector() { } + + Vector::Vector(const base& elts) : base(elts) { } + + Vector::~Vector() { } + + void + Vector::accept(Visitor& v) const { + v.visit(*this); + } + + // --------------------- + // -- Syntax::Visitor -- + // --------------------- + + // implicitly convert a reference to `T' to a reference to `S'. + template<typename S, typename T> + inline const S& + as(const T& t) { + return t; + } + + void + Syntax::Visitor::visit(const Integer& i) { + visit(as<Atom>(i)); + } + + void + Syntax::Visitor::visit(const String& s) { + visit(as<Atom>(s)); + } + + void + Syntax::Visitor::visit(const Symbol& s) { + visit(as<Atom>(s)); + } + + void + Syntax::Visitor::visit(const Reference& r) { + visit(as<Atom>(r)); + } + + // --------------- + // -- Allocator -- + // --------------- + Allocator::Allocator() : lists(4 * 1024), vectors(1024) { } + + // This destructor is defined here so that it provides + // a single instantiation point for destructors of all + // used templates floating around. + Allocator::~Allocator() { } + + const Integer* + Allocator::make_integer(const Token& t) { + return ints.allocate(t); + } + + const String* + Allocator::make_string(const Token& t) { + return strs.allocate(t); + } + + const Symbol* + Allocator::make_symbol(const Token& t, Symbol::Kind k) { + return syms.allocate(t, k); + } + + const Anchor* + Allocator::make_anchor(size_t t, const Syntax* s) { + return ancs.allocate(t, s); + } + + const Reference* + Allocator::make_reference(const Token& t, size_t i) { + return refs.allocate(t, i); + } + + const Quote* + Allocator::make_quote(const Syntax* s) { + return quotes.allocate(s); + } + + const Function* + Allocator::make_function(const Syntax* s) { + return funs.allocate(s); + } + + const Pair* + Allocator::make_pair(const Syntax* f, const Syntax* s) { + return pairs.allocate(f, s); + } + + const List* + Allocator::make_list(const std::vector<const Syntax*>& elts) { + if (elts.empty()) + return &empty_list; + return new(lists.allocate(1)) List(elts); + } + + const Vector* + Allocator::make_vector(const std::vector<const Syntax*>& elts) { + if (elts.empty()) + return &empty_vector; + return new(vectors.allocate(1)) Vector(elts); + } + + // ------------ + // -- Parser -- + // ------------ + + // Signal a parse error + static void + parse_error(const std::string& s) { + throw SystemError(s); + } + + // Signal that an expected syntax object was missing + static void + expected_syntax(const std::string& s) { + parse_error("expected " + s); + } + + // Signal an abrupt end of input + static void + unexpected_end_of_input(const std::string& s) { + parse_error("unexpected end of input after " + s); + } + + // Signal a missing closing parenthesis + static void + missing_closer_for(const std::string& s) { + parse_error("missing closing parenthesis for " + s); + } + + // The sequence of characters in [cur, last) consists + // entirely of digits. Return the corresponding natural value. + static size_t + natural_value(const char* cur, const char* last) { + size_t n = 0; + for (; cur < last; ++cur) + // FIXME: check for overflow. + n = 10 * n + (*cur - '0'); + return n; + } + + // Parse a plain identifier or a Lisp-style keyword identifier. + const Symbol* + Parser::parse_symbol(const Token*& cur, const Token* last) { + Symbol::Kind kind = *cur->lexeme->begin() == ':' + ? Symbol::keyword + : Symbol::ordinary; + return alloc.make_symbol(*cur++, kind); + } + + // Parse an anchor definition of the form #n=<syntax> + const Anchor* + Parser::parse_anchor(const Token*& cur, const Token* last) { + const size_t n = natural_value(cur->lexeme->begin() + 1, + cur->lexeme->end() - 1); + if (++cur == last) + unexpected_end_of_input("sharp-integer-equal sign"); + return alloc.make_anchor(n, parse_syntax(cur, last)); + } + + // Parse a reference to an anchor, #n# + const Reference* + Parser::parse_reference(const Token*& cur, const Token* last) { + const size_t n = natural_value(cur->lexeme->begin() + 1, + cur->lexeme->end() - 1); + return alloc.make_reference(*cur++, n); + } + + // Parse an uninterned symbol #:<identifier> + const Symbol* + Parser::parse_uninterned(const Token*& cur, const Token* last) { + if (cur == last or cur->type != Token::identifier) + expected_syntax("symbol after sharp-colon sign"); + // FIXME: check that the identifier is not a keyword. + return alloc.make_symbol(*cur++, Symbol::uninterned); + } + + // Parse a function syntax: #'<syntax> + const Function* + Parser::parse_function(const Token*& cur, const Token* last) { + if (cur == last) + unexpected_end_of_input("sharp-quote sign"); + return alloc.make_function(parse_syntax(cur, last)); + } + + // Parse a quotation + const Quote* + Parser::parse_quote(const Token*& cur, const Token* last) { + if (cur == last) + unexpected_end_of_input("quote sign"); + return alloc.make_quote(parse_syntax(cur, last)); + } + + // Parse a vector of syntax objects: #(s .. s) + const Vector* + Parser::parse_vector(const Token*& cur, const Token* last) { + std::vector<const Syntax*> elts; + while (cur < last and cur->type != Token::close_paren) + elts.push_back(parse_syntax(cur, last)); + if (cur == last) + missing_closer_for("vector"); + ++cur; + return alloc.make_vector(elts); + } + + // Constructs a pair or a list syntax object. + // This function is hairy for three reasons: (a) it is not known + // whether we list or a pair until after we have seen the + // enclosed tokens; (b) a dot is allowed at most once; (c) Lisp-style + // improper lists are not allowed. + const Syntax* + Parser::parse_list_or_pair(const Token*& cur, const Token* last) { + std::vector<const Syntax*> elts; + bool saw_dot = false; + while (cur < last and cur->type != Token::close_paren) { + if (cur->type == Token::dot) { + if (elts.size() != 1) + parse_error("unexpected dot sign"); + saw_dot = true; + ++cur; + continue; + } + elts.push_back(parse_syntax(cur, last)); + if (saw_dot && elts.size() == 2) + break; + } + if (cur == last or cur->type != Token::close_paren) + missing_closer_for(saw_dot ? "pair" : "list"); + ++cur; + if (saw_dot) + return alloc.make_pair(elts.front(), elts.back()); + return alloc.make_list(elts); + } + + Parser::Parser(Allocator& a, std::vector<const Syntax*>& v) + : alloc(a), syns(v) { } + + const Syntax* + Parser::parse_syntax(const Token*& cur, const Token* last) { + switch (cur->type) { + case Token::integer: + return alloc.make_integer(*cur++); + + case Token::string: + return alloc.make_string(*cur++); + + case Token::identifier: + return parse_symbol(cur, last); + + case Token::sharp_integer_equal: + return parse_anchor(cur, last); + + case Token::sharp_integer_sharp: + return parse_reference(cur, last); + + case Token::sharp_colon: + return parse_uninterned(++cur, last); + + case Token::sharp_apostrophe: + return parse_function(++cur, last); + + case Token::sharp_open_paren: + return parse_vector(++cur, last); + + case Token::apostrophe: + return parse_quote(++cur, last); + + case Token::open_paren: + return parse_list_or_pair(++cur, last); + + default: + parse_error(std::string("parse error before ") + + cur->lexeme->begin()); + return 0; // never executed + } + } + + const Token* + Parser::parse(const Token* cur, const Token* last) { + while (cur < last) + syns.push_back(parse_syntax(cur, last)); + return cur; + } + } +} |