SeExpr
BasicExpression.h
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1/*
2* Copyright Disney Enterprises, Inc. All rights reserved.
3*
4* Licensed under the Apache License, Version 2.0 (the "License");
5* you may not use this file except in compliance with the License
6* and the following modification to it: Section 6 Trademarks.
7* deleted and replaced with:
8*
9* 6. Trademarks. This License does not grant permission to use the
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11* Licensor and its affiliates, except as required for reproducing
12* the content of the NOTICE file.
13*
14* You may obtain a copy of the License at
15* http://www.apache.org/licenses/LICENSE-2.0
16*
17* @file BasicExpression.h
18* @brief A basic expression context for the expression previewer
19* @author aselle
20*/
21
22#ifndef BasicExpression_h
23#define BasicExpression_h
24
25#include <map>
26#include <SeExpr2/Expression.h>
27#include <SeExpr2/ExprFunc.h>
28#include <SeExpr2/ExprNode.h>
29
31 public:
33 double value;
34 ScalarRef() : SeExpr2::ExprVarRef(SeExpr2::ExprType().FP(1).Varying()), value(0.0) {}
35 void eval(double* result) { result[0] = value; }
36 void eval(const char** result) { assert(false); }
37 };
38
41 VectorRef() : SeExpr2::ExprVarRef(SeExpr2::ExprType().FP(3).Varying()), value(0.0) {}
42 void eval(double* result) {
43 for (int k = 0; k < 3; k++) result[k] = value[k];
44 };
45 void eval(const char** result) {
46 assert(false);
47 };
48 };
49
52 virtual ~DummyFuncX() {}
53
55 bool scalarWanted,
56 SeExpr2::ExprVarEnvBuilder& envBuilder) const {
57 bool valid = true;
58 int nargs = node->numChildren();
59 for (int i = 0; i < nargs; i++)
60 valid &= node->checkArg(i, SeExpr2::ExprType().FP(3).Constant(), envBuilder);
61 return valid ? SeExpr2::ExprType().FP(3).Varying() : SeExpr2::ExprType().Error();
62 }
63
67
68 virtual void eval(ArgHandle args) {
69 double* out = &args.outFp;
70 for (int i = 0; i < 3; i++) out[i] = 0.0;
71 }
74
75 mutable ScalarRef u;
76 mutable ScalarRef v;
77 mutable VectorRef P;
78
79 typedef std::map<std::string, VectorRef*> VARMAP;
80 mutable VARMAP varmap;
81 typedef std::map<std::string, bool> FUNCMAP;
83
84 BasicExpression(const std::string& expr, const SeExpr2::ExprType& type = SeExpr2::ExprType().FP(3));
85 virtual ~BasicExpression();
86
87 SeExpr2::ExprVarRef* resolveVar(const std::string& name) const;
88 SeExpr2::ExprFunc* resolveFunc(const std::string& name) const;
89 void setExpr(const std::string& str);
90 void clearVars();
91};
92
93#endif
SeExpr2::ExprFunc dummyFunc
SeExpr2::ExprFunc * resolveFunc(const std::string &name) const
virtual ~BasicExpression()
BasicExpression::DummyFuncX dummyFuncX
std::map< std::string, VectorRef * > VARMAP
std::map< std::string, bool > FUNCMAP
BasicExpression(const std::string &expr, const SeExpr2::ExprType &type=SeExpr2::ExprType().FP(3))
void setExpr(const std::string &str)
Node that calls a function.
Definition ExprNode.h:517
bool checkArg(int argIndex, ExprType type, ExprVarEnvBuilder &envBuilder)
Definition ExprNode.cpp:578
ExprFuncSimple(const bool threadSafe)
Definition ExprFuncX.h:74
Function Definition, used in parse tree and func table.
Definition ExprFunc.h:44
int numChildren() const
Number of children.
Definition ExprNode.h:114
ExprType & FP(int d)
Mutate this into a floating point type of dimension d.
Definition ExprType.h:90
ExprType & Error()
Mutate this into an error type.
Definition ExprType.h:102
ExprType & Varying()
Mutate this into a varying lifetime.
Definition ExprType.h:122
ExprType & Constant()
Mutate this into a constant lifetime.
Definition ExprType.h:112
Variable scope builder is used by the type checking and code gen to track visiblity of variables and ...
Definition ExprEnv.h:148
abstract class for implementing variable references
Definition Expression.h:45
main expression class
Definition Expression.h:76
virtual SeExpr2::ExprFuncNode::Data * evalConstant(const SeExpr2::ExprFuncNode *node, ArgHandle args) const
virtual SeExpr2::ExprType prep(SeExpr2::ExprFuncNode *node, bool scalarWanted, SeExpr2::ExprVarEnvBuilder &envBuilder) const
virtual void eval(ArgHandle args)
void eval(double *result)
returns this variable's value by setting result
void eval(const char **result)
void eval(const char **result)
void eval(double *result)
returns this variable's value by setting result
base class for custom instance data
Definition ExprNode.h:570
</pre >< h3 > Binding our variable reference</h3 > If we now tried to use the variable would still not be found by our expressions To make it bindable we need to override the resolveVar() function as follows</pre >< h3 > Variable setting</h3 > Next we need to make a way of setting the variable As the controlling code will use the expression it will repeatedly alternate between setting the independent variables that are used and calling evaluate(). What it has to do depends very much on the application. In this case we only need to set the independent variable x as</pre >< h2 > Evaluating expressions</h2 > Evaluating an expression is pretty easy But before we can do that we need to make an instance< pre > GrapherExpr expr("x+x^2")
</pre > Once we have this we need an instance to store our variable and provide a reference to that We make it because resolveVar() is const . One does not need to store a variable reference in a given expression. In fact