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1
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2 /* Compiler implementation of the D programming language
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3 * Copyright (C) 1999-2019 by The D Language Foundation, All Rights Reserved
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4 * written by Walter Bright
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5 * http://www.digitalmars.com
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6 * Distributed under the Boost Software License, Version 1.0.
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7 * http://www.boost.org/LICENSE_1_0.txt
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8 * https://github.com/D-Programming-Language/dmd/blob/master/src/staticcond.c
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9 */
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10
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11 #include "mars.h"
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12 #include "expression.h"
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13 #include "mtype.h"
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14 #include "scope.h"
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15
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16 Expression *semantic(Expression *e, Scope *sc);
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17
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18 /********************************************
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19 * Semantically analyze and then evaluate a static condition at compile time.
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20 * This is special because short circuit operators &&, || and ?: at the top
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21 * level are not semantically analyzed if the result of the expression is not
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22 * necessary.
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23 * Params:
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24 * exp = original expression, for error messages
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25 * Returns:
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26 * true if evaluates to true
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27 */
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28
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29 bool evalStaticCondition(Scope *sc, Expression *exp, Expression *e, bool &errors)
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30 {
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31 if (e->op == TOKandand)
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32 {
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33 AndAndExp *aae = (AndAndExp *)e;
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34 bool result = evalStaticCondition(sc, exp, aae->e1, errors);
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35 if (errors || !result)
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36 return false;
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37 result = evalStaticCondition(sc, exp, aae->e2, errors);
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38 return !errors && result;
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39 }
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40
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41 if (e->op == TOKoror)
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42 {
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43 OrOrExp *ooe = (OrOrExp *)e;
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44 bool result = evalStaticCondition(sc, exp, ooe->e1, errors);
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45 if (errors)
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46 return false;
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47 if (result)
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48 return true;
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49 result = evalStaticCondition(sc, exp, ooe->e2, errors);
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50 return !errors && result;
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51 }
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52
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53 if (e->op == TOKquestion)
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54 {
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55 CondExp *ce = (CondExp *)e;
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56 bool result = evalStaticCondition(sc, exp, ce->econd, errors);
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57 if (errors)
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58 return false;
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59 Expression *leg = result ? ce->e1 : ce->e2;
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60 result = evalStaticCondition(sc, exp, leg, errors);
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61 return !errors && result;
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62 }
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63
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64 unsigned nerrors = global.errors;
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65
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66 sc = sc->startCTFE();
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67 sc->flags |= SCOPEcondition;
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68
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69 e = semantic(e, sc);
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70 e = resolveProperties(sc, e);
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71
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72 sc = sc->endCTFE();
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73 e = e->optimize(WANTvalue);
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74
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75 if (nerrors != global.errors ||
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76 e->op == TOKerror ||
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77 e->type->toBasetype() == Type::terror)
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78 {
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79 errors = true;
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80 return false;
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81 }
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82
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83 if (!e->type->isBoolean())
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84 {
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85 exp->error("expression %s of type %s does not have a boolean value", exp->toChars(), e->type->toChars());
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86 errors = true;
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87 return false;
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88 }
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89
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90 e = e->ctfeInterpret();
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91
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92 if (e->isBool(true))
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93 return true;
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94 else if (e->isBool(false))
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95 return false;
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96
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97 e->error("expression %s is not constant", e->toChars());
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98 errors = true;
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99 return false;
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100 }
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