--Copyright (C) 2007, 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. )abbrev domain SYNTAX Syntax ++ Author: Gabriel Dos Reis ++ Date Created: November 10, 2007 ++ Date Last Updated: December 05, 2007 ++ Description: This domain provides a simple, general, and arguably ++ complete representation of Spad programs as objects of a term algebra ++ built from ground terms of type boolean, integers, foats, symbols, ++ and strings. This domain differs from InputForm in that it represents ++ any entity from a Spad program, not just expressions. ++ Related Constructors: Boolean, Integer, Float, symbol, String, SExpression. ++ See Also: SExpression. ++ Fixme: Provide direct support for boolean values, arbritrary ++ precision float point values. Syntax(): Public == Private where Public ==> Join(UnionType, CoercibleTo(OutputForm)) with convert: % -> SExpression ++ convert(s) returns the s-expression representation of a syntax. convert: SExpression -> % ++ convert(s) converts an s-expression to syntax. Note, when `s' ++ is not an atom, it is expected that it designates a proper list, ++ e.g. a sequence of cons cell ending with nil. coerce: Integer -> % ++ coerce(i) injects the integer value `i' into the Syntax domain coerce: % -> Integer ++ coerce(i) extracts the integer value `i' from the Syntax domain coerce: DoubleFloat -> % ++ coerce(f) injects the float value `f' into the Syntax domain coerce: % -> DoubleFloat ++ coerce(f) extracts the float value `f' from the Syntax domain coerce: Symbol -> % ++ coerce(s) injects the symbol `s' into the Syntax domain. coerce: % -> Symbol ++ coerce(s) extracts the symbol `s' from the Syntax domain. coerce: String -> % ++ coerce(s) injects the string value `s' into the syntax domain coerce: % -> String ++ coerce(s) extract the string value `s' from the syntax domain buildSyntax: (Symbol, List %) -> % ++ buildSyntax(op, [a1, ..., an]) builds a syntax object for op(a1,...,an). buildSyntax: (%, List %) -> % ++ buildSyntax(op, [a1, ..., an]) builds a syntax object for op(a1,...,an). nil?: % -> Boolean ++ nil?(s) is true when `s' is a syntax for the constant nil. getOperator: % -> Union(Integer, DoubleFloat, Symbol, String, %) ++ getOperator(x) returns the operator, or tag, of the syntax `x'. ++ The return value is itself a syntax if `x' really is an ++ application of a function symbol as opposed to being an ++ atomic ground term. getOperands: % -> List % ++ getOperands(x) returns the list of operands to the operator in `x'. _case: (%, [|Integer|]) -> Boolean ++ x case Integer is true is x really is an Integer _case: (%, [|DoubleFloat|]) -> Boolean ++ x case DoubleFloat is true is x really is a DoubleFloat _case: (%, [|Symbol|]) -> Boolean ++ x case Symbol is true is x really is a Symbol _case: (%, [|String|]) -> Boolean ++ x case String is true is x really is a String Private ==> SExpression add rep(x: %): SExpression == x pretend SExpression per(x: SExpression): % == x pretend % s case Integer == integer? rep s s case DoubleFloat == float? rep s s case String == string? rep s s case Symbol == symbol? rep s convert(x: %): SExpression == rep x convert(x: SExpression): % == per x coerce(i: Integer): % == i pretend % ccoerce(i: %): Integer == i case Integer => i userError "invalid conversion target type" coerce(f: DoubleFloat): % == f pretend % coerce(f: %): DoubleFloat == f case DoubleFloat => f userError "invalid conversion target type" coerce(s: Symbol): % == s pretend % coerce(s: %): Symbol == s case Symbol => s userError "invalid conversion target type" coerce(s: String): % == s pretend % coerce(s: %): String == s case String => s userError "invalid conversion target type" buildSyntax(s: Symbol, l: List %): % == -- ??? ideally we should have overloaded operator `per' that convert -- from list of syntax to syntax. But the compiler is at the -- moment defective for non-exported overloaded operations. cons(s::%, l) pretend % buildSyntax(op: %, l: List %): % == cons(op, l) pretend % nil? x == null? rep x getOperator x == atom? rep x => userError "atom as operand to getOperator" op := car rep x symbol? op => symbol op integer? op => integer op float? op => float op string? op => string op convert op getOperands x == s := rep x atom? s => [] [per t for t in destruct cdr s]