35 lines
1.2 KiB
C
35 lines
1.2 KiB
C
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// Copyright (c) 1999 Microsoft Corporation. All rights reserved.
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//
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// Declaration of Expression.
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//
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#pragma once
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#include "engcontrol.h"
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// The expression class takes input of a well-formed expression in infix (the order appearing in the script source)
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// notation. The blocks are converted to postfix notation and appeanded to the given script's exprs list and followed
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// with an _end block.
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// A working stack is used to perform the conversion. The stack to use is passed by reference so that the same stack
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// may be used to evaluate multiple expressions. This allows the stack to grow as needed until it reaches the max size
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// needed to process the expressions, minimizing reallocation thereafter.
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class Expression
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{
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public:
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Expression(Script &script, SmartRef::Stack<ExprBlock> &stack, ExprBlocks *peblocks) : m_script(script), m_stack(stack), m_eblocks(peblocks ? *peblocks : m_script.exprs) {}
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// Note: For unary - (negation), use TOKEN_sub instead of TOKEN_op_minus.
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HRESULT Add(ExprBlock b) { if (b.k == ExprBlock::_end) {assert(false); return E_INVALIDARG;} return m_e.Add(b); }
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HRESULT Generate();
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private:
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HRESULT InfixToPostfix();
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private:
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ExprBlocks m_e;
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Script &m_script;
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SmartRef::Stack<ExprBlock> &m_stack;
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ExprBlocks &m_eblocks;
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};
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