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--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 ==> 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
convert: % -> 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
convert: % -> DoubleFloat
++ convert(f) extracts the float value `f' from the Syntax domain
coerce: Symbol -> %
++ coerce(s) injects the symbol `s' into the Syntax domain.
convert: % -> Symbol
++ convert(s) extracts the symbol `s' from the Syntax domain.
coerce: String -> %
++ coerce(s) injects the string value `s' into the syntax domain
convert: % -> String
++ convert(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).
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: (%, Domain) -> Boolean
++ x case t returns true if x really is of type t, e.g.
++ Integer, DoubleFloat, Symbol, String, or %.
Private ==> SExpression add
rep(x: %): SExpression ==
x pretend SExpression
per(x: SExpression): % ==
x pretend %
convert(x: %): SExpression ==
rep x
convert(x: SExpression): % ==
per x
coerce(i: Integer): % ==
i pretend %
convert(i: %): Integer ==
not integer? rep i => userError "invalid conversion target type"
i pretend Integer
coerce(f: DoubleFloat): % ==
f pretend %
convert(f: %): DoubleFloat ==
not float? rep f => userError "invalid conversion target type"
f pretend DoubleFloat
coerce(s: Symbol): % ==
s pretend %
convert(s: %): Symbol ==
not symbol? rep s => userError "invalid conversion target type"
s pretend Symbol
coerce(s: String): % ==
s pretend %
convert(s: %): String ==
not string? rep s => userError "invalid conversion target type"
s pretend String
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 %
getOperator x ==
atom? rep x => userError "atom as operand to getOperator"
s := car rep x
symbol? s => symbol s
integer? s => integer s
float? s => float s
string? s => string s
convert s
getOperands x ==
s := rep x
atom? s => []
[per t for t in destruct cdr s]
s case t ==
symbol? rep s => t is Symbol
integer? rep s => t is Integer
float? rep s => t is DoubleFloat
string? rep s => t is String
pair? rep s => t is %
false
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