mirror of https://github.com/DanilaFe/abacus
85 lines
2.7 KiB
Kotlin
85 lines
2.7 KiB
Kotlin
package org.nwapw.abacus.context
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import org.nwapw.abacus.number.NumberInterface
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import org.nwapw.abacus.plugin.NumberImplementation
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import org.nwapw.abacus.tree.Reducer
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import org.nwapw.abacus.tree.TreeNode
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/**
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* A context for the reduction of a [org.nwapw.abacus.tree.TreeNode] into a number.
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*
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* The reduction context is used to carry important state information captured at the beginning
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* of the reduction of an expression, such as the variables and the implementation in use.
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*
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* @property parent the parent of this context.
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* @property numberImplementation the implementation for numbers of this context.
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* @property reducer the reducer used by this context.
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*/
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open class EvaluationContext(val parent: EvaluationContext? = null,
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open val numberImplementation: NumberImplementation? = null,
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open val reducer: Reducer<NumberInterface>? = null) {
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/**
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* The map of variables in this context.
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*/
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protected val variableMap = mutableMapOf<String, NumberInterface>()
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/**
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* The map of definitions in this context.
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*/
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protected val definitionMap = mutableMapOf<String, TreeNode>()
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/**
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* The set of all variable names defined in this context.
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*/
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val variables: Set<String>
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get() = variableMap.keys
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/**
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* The set of all definition names defined in this context.
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*/
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val definitions: Set<String>
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get() = definitionMap.keys
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/**
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* The implementation inherited from this context's parent.
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*/
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val inheritedNumberImplementation: NumberImplementation
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by ChainSearchDelegate { numberImplementation }
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/**
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* The reducer inherited from this context's parent.
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*/
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val inheritedReducer: Reducer<NumberInterface>
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by ChainSearchDelegate { reducer }
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/**
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* The set of all variables in this context and its parents.
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*/
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val inheritedVariables: Set<String> by ChainAccumulateDelegate { variables }
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/**
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* The set of all definition in this context and its parents.
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*/
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val inheritedDefinitions: Set<String> by ChainAccumulateDelegate { definitions }
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/**
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* Create a new child instance of this context that is mutable.
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* @return the new child instance.
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*/
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fun mutableSubInstance(): MutableEvaluationContext = MutableEvaluationContext(this)
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/**
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* Gets a variable stored in this context.
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*/
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fun getVariable(name: String): NumberInterface? {
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return variableMap[name] ?: parent?.getVariable(name)
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}
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/**
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* Gets the definition stored in this context.
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*/
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fun getDefinition(name: String): TreeNode? {
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return definitionMap[name] ?: parent?.getDefinition(name)
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}
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}
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