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package com.sun.faces.facelets.compiler;


import com.sun.faces.facelets.el.ELText;

import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ExpressionFactory;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import java.io.IOException;

final class AttributeInstruction implements Instruction {
    private final String alias;

    private final String attr;

    private final ELText txt;
    

    public AttributeInstruction(String alias, String attr, ELText txt) {
        this.alias = alias;
        this.attr  = attr;
        this.txt   = txt;
    }

    public void write(FacesContext context) throws IOException {
        ResponseWriter out = context.getResponseWriter();
        try {
            ELContext elContext = context.getELContext();
            String val = txt.toString(elContext);
            if (val != null && val.length() != 0) {
                out.writeAttribute(attr, val, null);
            }
        } catch (ELException e) {
            throw new ELException(this.alias + ": " + e.getMessage(), e.getCause());
        } catch (Exception e) {
            throw new ELException(this.alias + ": " + e.getMessage(), e);
        }
    }

    public Instruction apply(ExpressionFactory factory, ELContext ctx) {
        ELText nt = this.txt.apply(factory, ctx);
        if (nt == this.txt) {
            return this;
        }

        return new AttributeInstruction(alias, attr, nt);
    }

    public boolean isLiteral() {
        return txt.isLiteral();
    }
}