1 /* 2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org> 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining 5 * a copy of this software and associated documentation files (the 6 * "Software"), to deal in the Software without restriction, including 7 * without limitation the rights to use, copy, modify, merge, publish, 8 * distribute, sublicense, and/or sell copies of the Software, and to 9 * permit persons to whom the Software is furnished to do so, subject to 10 * the following conditions: 11 * 12 * The above copyright notice and this permission notice shall be 13 * included in all copies or substantial portions of the Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 * SOFTWARE. 23 */ 24 25 using System; 26 using System.Collections.Generic; 27 28 /* 29 * A "word" is a function with a name. Words can be either native or 30 * interpreted; native words are implemented as some in-compiler special 31 * code. 32 * 33 * Some native words (not all of them) have a C implementation and can 34 * thus be part of the generated C code. Native words with no C 35 * implementation can be used only during compilation; this is typically 36 * the case for words that support the syntax (e.g. 'if'). 37 */ 38 39 abstract class Word { 40 41 /* 42 * The compiler context for this word. 43 */ 44 internal T0Comp TC { 45 get; private set; 46 } 47 48 /* 49 * Immediate words are executed immediately when encountered in the 50 * source code, even while compiling another word. 51 */ 52 internal bool Immediate { 53 get; set; 54 } 55 56 /* 57 * Each word has a unique name. Names are case-sensitive. 58 */ 59 internal string Name { 60 get; private set; 61 } 62 63 /* 64 * Words are allocated slot numbers when output code is generated. 65 */ 66 internal int Slot { 67 get; set; 68 } 69 70 /* 71 * Each word may have a known stack effect. 72 */ 73 internal SType StackEffect { 74 get; set; 75 } 76 77 internal Word(T0Comp owner, string name) 78 { 79 TC = owner; 80 Name = name; 81 StackEffect = SType.UNKNOWN; 82 } 83 84 /* 85 * Resolving a word means looking up all references to external 86 * words. 87 */ 88 internal virtual void Resolve() 89 { 90 } 91 92 /* 93 * Execute this word. If the word is native, then its code is 94 * run right away; if the word is interpreted, then the entry 95 * sequence is executed. 96 */ 97 internal virtual void Run(CPU cpu) 98 { 99 throw new Exception(String.Format( 100 "cannot run '{0}' at compile-time", Name)); 101 } 102 103 /* 104 * All words may have an explicit C implementations. To be part 105 * of the generated C code, a word must either be interpreted, 106 * or have an explicit C implementation, or both. 107 */ 108 internal string CCode { 109 get; set; 110 } 111 112 /* 113 * Get all words referenced from this one. This implies 114 * resolving the word. 115 */ 116 internal virtual List<Word> GetReferences() 117 { 118 return new List<Word>(); 119 } 120 121 /* 122 * Get all data blocks directly referenced from this one. This 123 * implies resolving the word. 124 */ 125 internal virtual List<ConstData> GetDataBlocks() 126 { 127 return new List<ConstData>(); 128 } 129 130 /* 131 * Produce the code elements for this word. 132 */ 133 internal virtual void GenerateCodeElements(List<CodeElement> dst) 134 { 135 throw new Exception("Word does not yield code elements"); 136 } 137 138 /* 139 * Compute/verify stack effect for this word. 140 */ 141 internal virtual void AnalyseFlow() 142 { 143 } 144 145 /* 146 * Get maximum data stack usage for this word. This is the number 147 * of extra slots that this word may need on the data stack. If 148 * the stack effect is not known, this returns -1. 149 */ 150 internal virtual int MaxDataStack { 151 get { 152 SType se = StackEffect; 153 if (!se.IsKnown) { 154 return -1; 155 } 156 if (se.NoExit) { 157 return 0; 158 } else { 159 return Math.Min(0, se.DataOut - se.DataIn); 160 } 161 } 162 } 163 164 /* 165 * Get maximum return stack usage for this word. 166 */ 167 internal virtual int MaxReturnStack { 168 get { 169 return 0; 170 } 171 } 172 } 173