name.martingeisse.phunky.runtime.code.expression.array.ArrayElementExpression.java Source code

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Here is the source code for name.martingeisse.phunky.runtime.code.expression.array.ArrayElementExpression.java

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/**
 * Copyright (c) 2010 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package name.martingeisse.phunky.runtime.code.expression.array;

import name.martingeisse.phunky.runtime.Environment;
import name.martingeisse.phunky.runtime.assignment.ArrayElementAssignmentTarget;
import name.martingeisse.phunky.runtime.assignment.AssignmentTarget;
import name.martingeisse.phunky.runtime.code.CodeDumper;
import name.martingeisse.phunky.runtime.code.expression.AbstractComputeExpression;
import name.martingeisse.phunky.runtime.code.expression.AbstractExpression;
import name.martingeisse.phunky.runtime.code.expression.AbstractVariableExpression;
import name.martingeisse.phunky.runtime.code.expression.Expression;
import name.martingeisse.phunky.runtime.json.JsonObjectBuilder;
import name.martingeisse.phunky.runtime.json.JsonValueBuilder;
import name.martingeisse.phunky.runtime.variable.PhpValueArray;
import name.martingeisse.phunky.runtime.variable.PhpVariableArray;
import name.martingeisse.phunky.runtime.variable.TypeConversionUtil;
import name.martingeisse.phunky.runtime.variable.Variable;

import org.apache.commons.lang3.tuple.Pair;

/**
 * This expression selects one element of an array.
 * 
 * This class does not inherit from either {@link AbstractVariableExpression} or
 * {@link AbstractComputeExpression} because it can behave like either
 * one, depending on the context in which it is used. 
 */
public final class ArrayElementExpression extends AbstractExpression {

    /**
     * the arrayExpression
     */
    private final Expression arrayExpression;

    /**
     * the keyExpression
     */
    private final Expression keyExpression;

    /**
     * Constructor.
     * @param arrayExpression the expression that determines the array
     * @param keyExpression the expression that determines the key
     */
    public ArrayElementExpression(final Expression arrayExpression, final Expression keyExpression) {
        this.arrayExpression = arrayExpression;
        this.keyExpression = keyExpression;
    }

    /**
     * Getter method for the arrayExpression.
     * @return the arrayExpression
     */
    public Expression getArrayExpression() {
        return arrayExpression;
    }

    /**
     * Getter method for the keyExpression.
     * @return the keyExpression
     */
    public Expression getKeyExpression() {
        return keyExpression;
    }

    /* (non-Javadoc)
     * @see name.martingeisse.phunky.runtime.code.expression.AbstractVariableExpression#evaluate(name.martingeisse.phunky.runtime.Environment)
     */
    @Override
    public Object evaluate(Environment environment) {
        Object arrayCandidate = arrayExpression.evaluate(environment);
        String key = TypeConversionUtil.convertToString(keyExpression.evaluate(environment));
        if (arrayCandidate instanceof PhpValueArray) {
            PhpValueArray array = (PhpValueArray) arrayCandidate;
            return array.getValueOrError(environment.getRuntime(), getLocation(), key);
        } else if (arrayCandidate instanceof String) {
            String s = (String) arrayCandidate;
            long index;
            try {
                index = Long.parseLong(key);
            } catch (NumberFormatException e) {
                environment.getRuntime().triggerError("Illegal string offset '" + key + "'",
                        keyExpression.getLocation());
                return null;
            }
            if (index < 0 || index >= s.length()) {
                return "";
            } else {
                int intIndex = (int) index;
                return s.substring(intIndex, intIndex + 1);
            }
        } else {
            environment.getRuntime().triggerError("trying to get element of non-array value", getLocation());
            return null;
        }
    }

    /* (non-Javadoc)
     * @see name.martingeisse.phunky.runtime.code.expression.Expression#evaluateForEmptyCheck(name.martingeisse.phunky.runtime.Environment)
     */
    @Override
    public Object evaluateForEmptyCheck(Environment environment) {
        Object arrayCandidate = arrayExpression.evaluateForEmptyCheck(environment);
        String key = TypeConversionUtil.convertToString(keyExpression.evaluate(environment));
        if (arrayCandidate instanceof PhpValueArray) {
            PhpValueArray array = (PhpValueArray) arrayCandidate;
            return array.getValue(key);
        } else {
            return null;
        }
    }

    /* (non-Javadoc)
     * @see name.martingeisse.phunky.runtime.code.expression.Expression#resolveAssignmentTarget(name.martingeisse.phunky.runtime.Environment)
     */
    @Override
    public AssignmentTarget resolveAssignmentTarget(Environment environment) {
        Pair<Variable, String> variableArrayAndKey = obtainArrayVariableAndKey(environment);
        if (variableArrayAndKey == null) {
            environment.getRuntime().triggerError("trying to get element of non-array value", getLocation());
            return null;
        } else {
            Variable arrayVariable = variableArrayAndKey.getLeft();
            String key = variableArrayAndKey.getRight();
            return new ArrayElementAssignmentTarget(array, key);
        }
    }

    /* (non-Javadoc)
     * @see name.martingeisse.phunky.runtime.code.expression.Expression#getOrCreateVariable(name.martingeisse.phunky.runtime.Environment)
     */
    @Override
    public Variable resolveOrCreateVariable(final Environment environment) {
        Pair<Variable, String> variableArrayAndKey = obtainArrayVariableAndKey(environment);
        if (variableArrayAndKey == null) {
            return null;
        } else {
            PhpVariableArray variableArray = variableArrayAndKey.getLeft()
                    .getVariableArray(environment.getRuntime(), getLocation());
            String key = variableArrayAndKey.getRight();
            return variableArray.getOrCreateVariable(key);
        }
    }

    /**
     * 
     */
    private Pair<Variable, String> obtainArrayVariableAndKey(Environment environment) {
        // note that arrays are a value type, so getting the variable for an element also gets the variable for the array
        Variable arrayVariable = arrayExpression.resolveOrCreateVariable(environment);
        String key = TypeConversionUtil.convertToString(keyExpression.evaluate(environment));
        if (arrayVariable == null) {
            environment.getRuntime().triggerError("cannot use this expression as an array: " + arrayExpression,
                    arrayExpression.getLocation());
            return null;
        }
        return Pair.of(arrayVariable, key);
    }

    /* (non-Javadoc)
     * @see name.martingeisse.phunky.runtime.code.expression.Expression#dump(name.martingeisse.phunky.runtime.code.CodeDumper)
     */
    @Override
    public void dump(final CodeDumper dumper) {
        arrayExpression.dump(dumper);
        dumper.print('[');
        keyExpression.dump(dumper);
        dumper.print(']');
    }

    /* (non-Javadoc)
     * @see name.martingeisse.phunky.runtime.code.statement.Statement#toJson(name.martingeisse.phunky.runtime.json.JsonValueBuilder)
     */
    @Override
    public void toJson(JsonValueBuilder<?> builder) {
        JsonObjectBuilder<?> sub = builder.object().property("type").string("arrayElement");
        arrayExpression.toJson(sub.property("array"));
        keyExpression.toJson(sub.property("key"));
        sub.end();
    }

}