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/*
* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
using System;
using System.Collections.Generic;
/*
* A "word" is a function with a name. Words can be either native or
* interpreted; native words are implemented as some in-compiler special
* code.
*
* Some native words (not all of them) have a C implementation and can
* thus be part of the generated C code. Native words with no C
* implementation can be used only during compilation; this is typically
* the case for words that support the syntax (e.g. 'if').
*/
abstract class Word {
/*
* The compiler context for this word.
*/
internal T0Comp TC {
get; private set;
}
/*
* Immediate words are executed immediately when encountered in the
* source code, even while compiling another word.
*/
internal bool Immediate {
get; set;
}
/*
* Each word has a unique name. Names are case-sensitive.
*/
internal string Name {
get; private set;
}
/*
* Words are allocated slot numbers when output code is generated.
*/
internal int Slot {
get; set;
}
/*
* Each word may have a known stack effect.
*/
internal SType StackEffect {
get; set;
}
internal Word(T0Comp owner, string name)
{
TC = owner;
Name = name;
StackEffect = SType.UNKNOWN;
}
/*
* Resolving a word means looking up all references to external
* words.
*/
internal virtual void Resolve()
{
}
/*
* Execute this word. If the word is native, then its code is
* run right away; if the word is interpreted, then the entry
* sequence is executed.
*/
internal virtual void Run(CPU cpu)
{
throw new Exception(String.Format(
"cannot run '{0}' at compile-time", Name));
}
/*
* All words may have an explicit C implementations. To be part
* of the generated C code, a word must either be interpreted,
* or have an explicit C implementation, or both.
*/
internal string CCode {
get; set;
}
/*
* Get all words referenced from this one. This implies
* resolving the word.
*/
internal virtual List<Word> GetReferences()
{
return new List<Word>();
}
/*
* Get all data blocks directly referenced from this one. This
* implies resolving the word.
*/
internal virtual List<ConstData> GetDataBlocks()
{
return new List<ConstData>();
}
/*
* Produce the code elements for this word.
*/
internal virtual void GenerateCodeElements(List<CodeElement> dst)
{
throw new Exception("Word does not yield code elements");
}
/*
* Compute/verify stack effect for this word.
*/
internal virtual void AnalyseFlow()
{
}
/*
* Get maximum data stack usage for this word. This is the number
* of extra slots that this word may need on the data stack. If
* the stack effect is not known, this returns -1.
*/
internal virtual int MaxDataStack {
get {
SType se = StackEffect;
if (!se.IsKnown) {
return -1;
}
if (se.NoExit) {
return 0;
} else {
return Math.Min(0, se.DataOut - se.DataIn);
}
}
}
/*
* Get maximum return stack usage for this word.
*/
internal virtual int MaxReturnStack {
get {
return 0;
}
}
}
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