////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2017 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package net.sf.saxon.trace;

import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.Literal;
import net.sf.saxon.expr.StaticContext;
import net.sf.saxon.expr.flwor.Clause;
import net.sf.saxon.expr.flwor.TraceClause;
import net.sf.saxon.expr.instruct.TraceExpression;
import net.sf.saxon.expr.parser.CodeInjector;
import net.sf.saxon.om.StandardNames;
import net.sf.saxon.om.StructuredQName;

/**
 * A code injector that wraps every expression (other than a literal) in a TraceExpression, which causes
 * a TraceListener to be notified when the expression is evaluated
 */
public class TraceCodeInjector implements CodeInjector {

    /**
     * If tracing, wrap an expression in a trace instruction
     *
     * @param exp       the expression to be wrapped
     * @param env       the static context
     * @param construct integer constant identifying the kind of construct
     * @param qName     the name of the construct (if applicable)
     * @return the expression that does the tracing
     */

    public Expression inject(Expression exp, /*@NotNull*/ StaticContext env, int construct, StructuredQName qName) {
        if (exp instanceof Literal && !(construct == StandardNames.XSL_TEMPLATE || construct == StandardNames.XSL_FUNCTION)) {
            return exp;
        }
        TraceExpression trace = new TraceExpression(exp);
        //ExpressionTool.copyLocationInfo(exp, trace);
        trace.setNamespaceResolver(env.getNamespaceResolver());
        trace.setConstructType(construct);
        trace.setObjectName(qName);
        //trace.setObjectNameCode(objectNameCode);
        return trace;
    }

    /**
     * If tracing, add a clause to a FLWOR expression that can be used to monitor requests for
     * tuples to be processed
     *
     * @param target    the clause whose evaluation is to be traced (or otherwise monitored)
     * @param env       the static context of the containing FLWOR expression
     * @return the new clause to do the tracing; or null if no tracing is required at this point
     */

    public Clause injectClause(Clause target, StaticContext env) {
        return new TraceClause(target, env.getNamespaceResolver());
    }
}

