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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2008-2013, fluid Operations AG<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * FedX is free software: you can redistribute it and/or modify<a name="line.4"></a>
<span class="sourceLineNo">005</span> * it under the terms of the GNU Affero General Public License as<a name="line.5"></a>
<span class="sourceLineNo">006</span> * published by the Free Software Foundation, either version 3 of the<a name="line.6"></a>
<span class="sourceLineNo">007</span> * License, or (at your option) any later version.<a name="line.7"></a>
<span class="sourceLineNo">008</span> * <a name="line.8"></a>
<span class="sourceLineNo">009</span> * This program is distributed in the hope that it will be useful,<a name="line.9"></a>
<span class="sourceLineNo">010</span> * but WITHOUT ANY WARRANTY; without even the implied warranty of<a name="line.10"></a>
<span class="sourceLineNo">011</span> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the<a name="line.11"></a>
<span class="sourceLineNo">012</span> * GNU Affero General Public License for more details.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * <a name="line.13"></a>
<span class="sourceLineNo">014</span> * You should have received a copy of the GNU Affero General Public License<a name="line.14"></a>
<span class="sourceLineNo">015</span> * along with this program.  If not, see &lt;http://www.gnu.org/licenses/&gt;.<a name="line.15"></a>
<span class="sourceLineNo">016</span> */<a name="line.16"></a>
<span class="sourceLineNo">017</span><a name="line.17"></a>
<span class="sourceLineNo">018</span>package com.fluidops.fedx.optimizer;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import java.util.ArrayList;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.util.HashSet;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.util.List;<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span>import org.apache.log4j.Logger;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import org.openrdf.model.Resource;<a name="line.25"></a>
<span class="sourceLineNo">026</span>import org.openrdf.model.Value;<a name="line.26"></a>
<span class="sourceLineNo">027</span>import org.openrdf.query.Binding;<a name="line.27"></a>
<span class="sourceLineNo">028</span>import org.openrdf.query.algebra.And;<a name="line.28"></a>
<span class="sourceLineNo">029</span>import org.openrdf.query.algebra.Compare;<a name="line.29"></a>
<span class="sourceLineNo">030</span>import org.openrdf.query.algebra.Filter;<a name="line.30"></a>
<span class="sourceLineNo">031</span>import org.openrdf.query.algebra.Not;<a name="line.31"></a>
<span class="sourceLineNo">032</span>import org.openrdf.query.algebra.Or;<a name="line.32"></a>
<span class="sourceLineNo">033</span>import org.openrdf.query.algebra.Projection;<a name="line.33"></a>
<span class="sourceLineNo">034</span>import org.openrdf.query.algebra.QueryModelNode;<a name="line.34"></a>
<span class="sourceLineNo">035</span>import org.openrdf.query.algebra.Service;<a name="line.35"></a>
<span class="sourceLineNo">036</span>import org.openrdf.query.algebra.TupleExpr;<a name="line.36"></a>
<span class="sourceLineNo">037</span>import org.openrdf.query.algebra.ValueConstant;<a name="line.37"></a>
<span class="sourceLineNo">038</span>import org.openrdf.query.algebra.ValueExpr;<a name="line.38"></a>
<span class="sourceLineNo">039</span>import org.openrdf.query.algebra.Var;<a name="line.39"></a>
<span class="sourceLineNo">040</span>import org.openrdf.query.algebra.helpers.QueryModelVisitorBase;<a name="line.40"></a>
<span class="sourceLineNo">041</span>import org.openrdf.query.impl.BindingImpl;<a name="line.41"></a>
<span class="sourceLineNo">042</span><a name="line.42"></a>
<span class="sourceLineNo">043</span>import com.fluidops.fedx.algebra.EmptyResult;<a name="line.43"></a>
<span class="sourceLineNo">044</span>import com.fluidops.fedx.algebra.FilterExpr;<a name="line.44"></a>
<span class="sourceLineNo">045</span>import com.fluidops.fedx.algebra.FilterTuple;<a name="line.45"></a>
<span class="sourceLineNo">046</span>import com.fluidops.fedx.algebra.ProjectionWithBindings;<a name="line.46"></a>
<span class="sourceLineNo">047</span>import com.fluidops.fedx.algebra.StatementTupleExpr;<a name="line.47"></a>
<span class="sourceLineNo">048</span>import com.fluidops.fedx.exception.OptimizationException;<a name="line.48"></a>
<span class="sourceLineNo">049</span><a name="line.49"></a>
<span class="sourceLineNo">050</span>/**<a name="line.50"></a>
<span class="sourceLineNo">051</span> * Filter optimizer to push down FILTER expressions as far as possible.<a name="line.51"></a>
<span class="sourceLineNo">052</span> * <a name="line.52"></a>
<span class="sourceLineNo">053</span> * @author Andreas Schwarte<a name="line.53"></a>
<span class="sourceLineNo">054</span> *<a name="line.54"></a>
<span class="sourceLineNo">055</span> */<a name="line.55"></a>
<span class="sourceLineNo">056</span>public class FilterOptimizer extends QueryModelVisitorBase&lt;OptimizationException&gt; implements FedXOptimizer {<a name="line.56"></a>
<span class="sourceLineNo">057</span><a name="line.57"></a>
<span class="sourceLineNo">058</span>        public static Logger log = Logger.getLogger(FilterOptimizer.class);<a name="line.58"></a>
<span class="sourceLineNo">059</span>        <a name="line.59"></a>
<span class="sourceLineNo">060</span>        /* map containing the inserted values, i.e. filter values which could be<a name="line.60"></a>
<span class="sourceLineNo">061</span>         * directly replaced into the query<a name="line.61"></a>
<span class="sourceLineNo">062</span>         */<a name="line.62"></a>
<span class="sourceLineNo">063</span>        private List&lt;Binding&gt; insertedValues = new ArrayList&lt;Binding&gt;();<a name="line.63"></a>
<span class="sourceLineNo">064</span>        <a name="line.64"></a>
<span class="sourceLineNo">065</span>        @Override<a name="line.65"></a>
<span class="sourceLineNo">066</span>        public void optimize(TupleExpr tupleExpr) {<a name="line.66"></a>
<span class="sourceLineNo">067</span>                tupleExpr.visit(this);                          <a name="line.67"></a>
<span class="sourceLineNo">068</span>        }<a name="line.68"></a>
<span class="sourceLineNo">069</span><a name="line.69"></a>
<span class="sourceLineNo">070</span>        <a name="line.70"></a>
<span class="sourceLineNo">071</span>        @Override<a name="line.71"></a>
<span class="sourceLineNo">072</span>        public void meet(Filter filter)  {<a name="line.72"></a>
<span class="sourceLineNo">073</span>                <a name="line.73"></a>
<span class="sourceLineNo">074</span>                if (filter.getArg() instanceof EmptyResult) {<a name="line.74"></a>
<span class="sourceLineNo">075</span>                        log.debug("Argument of filter expression does not yield results at the provided sources, replacing Filter node.");<a name="line.75"></a>
<span class="sourceLineNo">076</span>                        filter.replaceWith(filter.getArg());<a name="line.76"></a>
<span class="sourceLineNo">077</span>                        return;<a name="line.77"></a>
<span class="sourceLineNo">078</span>                }<a name="line.78"></a>
<span class="sourceLineNo">079</span>                                        <a name="line.79"></a>
<span class="sourceLineNo">080</span>                /*<a name="line.80"></a>
<span class="sourceLineNo">081</span>                 * TODO idea:<a name="line.81"></a>
<span class="sourceLineNo">082</span>                 * if we have a FILTER such as ?s='a' OR ?s='b' OR ?s='c' handle this appropriately<a name="line.82"></a>
<span class="sourceLineNo">083</span>                 */<a name="line.83"></a>
<span class="sourceLineNo">084</span>                <a name="line.84"></a>
<span class="sourceLineNo">085</span>                ValueExpr valueExpr = filter.getCondition();<a name="line.85"></a>
<span class="sourceLineNo">086</span>                <a name="line.86"></a>
<span class="sourceLineNo">087</span>                /*<a name="line.87"></a>
<span class="sourceLineNo">088</span>                 * TODO transform condition into some normal form, e.g. CNF<a name="line.88"></a>
<span class="sourceLineNo">089</span>                 */<a name="line.89"></a>
<span class="sourceLineNo">090</span>                <a name="line.90"></a>
<span class="sourceLineNo">091</span>                // determine conjunctive expressions<a name="line.91"></a>
<span class="sourceLineNo">092</span>                List&lt;ValueExpr&gt; conjunctiveExpressions = new ArrayList&lt;ValueExpr&gt;();<a name="line.92"></a>
<span class="sourceLineNo">093</span>                getConjunctiveExpressions(valueExpr, conjunctiveExpressions);<a name="line.93"></a>
<span class="sourceLineNo">094</span>                                <a name="line.94"></a>
<span class="sourceLineNo">095</span>                FilterExprInsertVisitor filterExprVst = new FilterExprInsertVisitor();<a name="line.95"></a>
<span class="sourceLineNo">096</span>                List&lt;ValueExpr&gt; remainingExpr = new ArrayList&lt;ValueExpr&gt;(conjunctiveExpressions.size());<a name="line.96"></a>
<span class="sourceLineNo">097</span>                <a name="line.97"></a>
<span class="sourceLineNo">098</span>                for (ValueExpr cond : conjunctiveExpressions) {<a name="line.98"></a>
<span class="sourceLineNo">099</span>                        <a name="line.99"></a>
<span class="sourceLineNo">100</span>                        /*<a name="line.100"></a>
<span class="sourceLineNo">101</span>                         * Determine if this filter is applicable for optimization.<a name="line.101"></a>
<span class="sourceLineNo">102</span>                         * Currently only leaf expressions are applicable, i.e.<a name="line.102"></a>
<span class="sourceLineNo">103</span>                         * not combined expressions.<a name="line.103"></a>
<span class="sourceLineNo">104</span>                         */<a name="line.104"></a>
<span class="sourceLineNo">105</span>                        if (isCompatibleExpr(cond)) {<a name="line.105"></a>
<span class="sourceLineNo">106</span>                                                        <a name="line.106"></a>
<span class="sourceLineNo">107</span>                                HashSet&lt;String&gt; exprVars = new VarFinder().findVars(cond);<a name="line.107"></a>
<span class="sourceLineNo">108</span>                                FilterExpr filterExpr = new FilterExpr(cond, exprVars);<a name="line.108"></a>
<span class="sourceLineNo">109</span>                                <a name="line.109"></a>
<span class="sourceLineNo">110</span>                                filterExprVst.initialize(filterExpr);<a name="line.110"></a>
<span class="sourceLineNo">111</span>                                filter.getArg().visit(filterExprVst);<a name="line.111"></a>
<span class="sourceLineNo">112</span>                                <a name="line.112"></a>
<span class="sourceLineNo">113</span>                                // if the filter expr. is handled in the stmt we do not have to keep it<a name="line.113"></a>
<span class="sourceLineNo">114</span>                                if (filterExprVst.canRemove())<a name="line.114"></a>
<span class="sourceLineNo">115</span>                                        continue;<a name="line.115"></a>
<span class="sourceLineNo">116</span>                                <a name="line.116"></a>
<span class="sourceLineNo">117</span>                                remainingExpr.add(filterExpr.getExpression());<a name="line.117"></a>
<span class="sourceLineNo">118</span>                                <a name="line.118"></a>
<span class="sourceLineNo">119</span>                        } else {<a name="line.119"></a>
<span class="sourceLineNo">120</span>                                remainingExpr.add(cond);<a name="line.120"></a>
<span class="sourceLineNo">121</span>                        }<a name="line.121"></a>
<span class="sourceLineNo">122</span>                        <a name="line.122"></a>
<span class="sourceLineNo">123</span>                }<a name="line.123"></a>
<span class="sourceLineNo">124</span>                <a name="line.124"></a>
<span class="sourceLineNo">125</span>                if (remainingExpr.size()==0) {<a name="line.125"></a>
<span class="sourceLineNo">126</span>                        filter.replaceWith(filter.getArg());    // remove the filter                    <a name="line.126"></a>
<span class="sourceLineNo">127</span>                }<a name="line.127"></a>
<span class="sourceLineNo">128</span>                <a name="line.128"></a>
<span class="sourceLineNo">129</span>                else if (remainingExpr.size()==1) {<a name="line.129"></a>
<span class="sourceLineNo">130</span>                        filter.setCondition(remainingExpr.get(0));              // just apply the remaining condition<a name="line.130"></a>
<span class="sourceLineNo">131</span>                }<a name="line.131"></a>
<span class="sourceLineNo">132</span>                <a name="line.132"></a>
<span class="sourceLineNo">133</span>                else {<a name="line.133"></a>
<span class="sourceLineNo">134</span>                        <a name="line.134"></a>
<span class="sourceLineNo">135</span>                        // construct conjunctive value expr<a name="line.135"></a>
<span class="sourceLineNo">136</span>                        And root = new And();   <a name="line.136"></a>
<span class="sourceLineNo">137</span>                        root.setLeftArg(remainingExpr.get(0));<a name="line.137"></a>
<span class="sourceLineNo">138</span>                        And tmp = root;<a name="line.138"></a>
<span class="sourceLineNo">139</span>                        for (int i=1; i&lt;remainingExpr.size()-1; i++) {<a name="line.139"></a>
<span class="sourceLineNo">140</span>                                And _a = new And();<a name="line.140"></a>
<span class="sourceLineNo">141</span>                                _a.setLeftArg(remainingExpr.get(i));<a name="line.141"></a>
<span class="sourceLineNo">142</span>                                tmp.setRightArg(_a);<a name="line.142"></a>
<span class="sourceLineNo">143</span>                                tmp = _a;                               <a name="line.143"></a>
<span class="sourceLineNo">144</span>                        }<a name="line.144"></a>
<span class="sourceLineNo">145</span>                        tmp.setRightArg(remainingExpr.get(remainingExpr.size()-1));<a name="line.145"></a>
<span class="sourceLineNo">146</span>                        <a name="line.146"></a>
<span class="sourceLineNo">147</span>                        filter.setCondition(root);<a name="line.147"></a>
<span class="sourceLineNo">148</span>                }<a name="line.148"></a>
<span class="sourceLineNo">149</span>                <a name="line.149"></a>
<span class="sourceLineNo">150</span>        }<a name="line.150"></a>
<span class="sourceLineNo">151</span>                <a name="line.151"></a>
<span class="sourceLineNo">152</span>        <a name="line.152"></a>
<span class="sourceLineNo">153</span>        <a name="line.153"></a>
<span class="sourceLineNo">154</span>        @Override<a name="line.154"></a>
<span class="sourceLineNo">155</span>        public void meet(Projection node) throws OptimizationException {<a name="line.155"></a>
<span class="sourceLineNo">156</span>                super.meet(node);<a name="line.156"></a>
<span class="sourceLineNo">157</span>                // we need to check if we have inserted some value constant<a name="line.157"></a>
<span class="sourceLineNo">158</span>                // from a filter and if this is part of the projection. If yes<a name="line.158"></a>
<span class="sourceLineNo">159</span>                // we need to actually project it<a name="line.159"></a>
<span class="sourceLineNo">160</span>                if (!insertedValues.isEmpty()) {<a name="line.160"></a>
<span class="sourceLineNo">161</span>                        node.replaceWith(new ProjectionWithBindings(node.getArg(), node.getProjectionElemList(), insertedValues));<a name="line.161"></a>
<span class="sourceLineNo">162</span>                }<a name="line.162"></a>
<span class="sourceLineNo">163</span>        }<a name="line.163"></a>
<span class="sourceLineNo">164</span><a name="line.164"></a>
<span class="sourceLineNo">165</span><a name="line.165"></a>
<span class="sourceLineNo">166</span>        @Override<a name="line.166"></a>
<span class="sourceLineNo">167</span>        public void meet(Service node) throws OptimizationException     {<a name="line.167"></a>
<span class="sourceLineNo">168</span>                // do not optimize anything within SERVICE<a name="line.168"></a>
<span class="sourceLineNo">169</span>        }<a name="line.169"></a>
<span class="sourceLineNo">170</span><a name="line.170"></a>
<span class="sourceLineNo">171</span><a name="line.171"></a>
<span class="sourceLineNo">172</span>        /**<a name="line.172"></a>
<span class="sourceLineNo">173</span>         * add the conjunctive expressions to specified list, has recursive step.<a name="line.173"></a>
<span class="sourceLineNo">174</span>         *<a name="line.174"></a>
<span class="sourceLineNo">175</span>         * @param expr<a name="line.175"></a>
<span class="sourceLineNo">176</span>         *                      the expr, in the best case in CNF<a name="line.176"></a>
<span class="sourceLineNo">177</span>         * @param conjExpr<a name="line.177"></a>
<span class="sourceLineNo">178</span>         *                      the list to which expressions will be added<a name="line.178"></a>
<span class="sourceLineNo">179</span>         */<a name="line.179"></a>
<span class="sourceLineNo">180</span>        protected void getConjunctiveExpressions(ValueExpr expr, List&lt;ValueExpr&gt; conjExpr) {<a name="line.180"></a>
<span class="sourceLineNo">181</span>                if (expr instanceof And) {<a name="line.181"></a>
<span class="sourceLineNo">182</span>                        And and = (And)expr;<a name="line.182"></a>
<span class="sourceLineNo">183</span>                        getConjunctiveExpressions(and.getLeftArg(), conjExpr);<a name="line.183"></a>
<span class="sourceLineNo">184</span>                        getConjunctiveExpressions(and.getRightArg(), conjExpr);<a name="line.184"></a>
<span class="sourceLineNo">185</span>                } else<a name="line.185"></a>
<span class="sourceLineNo">186</span>                        conjExpr.add(expr);<a name="line.186"></a>
<span class="sourceLineNo">187</span>        }<a name="line.187"></a>
<span class="sourceLineNo">188</span>        <a name="line.188"></a>
<span class="sourceLineNo">189</span>        <a name="line.189"></a>
<span class="sourceLineNo">190</span>        /**<a name="line.190"></a>
<span class="sourceLineNo">191</span>         * returns true if this filter can be used for optimization. Currently no<a name="line.191"></a>
<span class="sourceLineNo">192</span>         * conjunctive or disjunctive expressions are supported.<a name="line.192"></a>
<span class="sourceLineNo">193</span>         * <a name="line.193"></a>
<span class="sourceLineNo">194</span>         * @param e<a name="line.194"></a>
<span class="sourceLineNo">195</span>         * @return<a name="line.195"></a>
<span class="sourceLineNo">196</span>         */<a name="line.196"></a>
<span class="sourceLineNo">197</span>        protected boolean isCompatibleExpr(ValueExpr e) {<a name="line.197"></a>
<span class="sourceLineNo">198</span>                <a name="line.198"></a>
<span class="sourceLineNo">199</span>                if (e instanceof And || e instanceof Or) {<a name="line.199"></a>
<span class="sourceLineNo">200</span>                        return false;<a name="line.200"></a>
<span class="sourceLineNo">201</span>                }<a name="line.201"></a>
<span class="sourceLineNo">202</span>                <a name="line.202"></a>
<span class="sourceLineNo">203</span>                if (e instanceof Not) {<a name="line.203"></a>
<span class="sourceLineNo">204</span>                        return isCompatibleExpr( ((Not)e).getArg() );<a name="line.204"></a>
<span class="sourceLineNo">205</span>                }<a name="line.205"></a>
<span class="sourceLineNo">206</span>                <a name="line.206"></a>
<span class="sourceLineNo">207</span>                return true;<a name="line.207"></a>
<span class="sourceLineNo">208</span>        }<a name="line.208"></a>
<span class="sourceLineNo">209</span>        <a name="line.209"></a>
<span class="sourceLineNo">210</span>        <a name="line.210"></a>
<span class="sourceLineNo">211</span>        <a name="line.211"></a>
<span class="sourceLineNo">212</span>        protected class VarFinder extends QueryModelVisitorBase&lt;OptimizationException&gt; {<a name="line.212"></a>
<span class="sourceLineNo">213</span>                <a name="line.213"></a>
<span class="sourceLineNo">214</span>                protected HashSet&lt;String&gt; vars;<a name="line.214"></a>
<span class="sourceLineNo">215</span>                <a name="line.215"></a>
<span class="sourceLineNo">216</span>                public HashSet&lt;String&gt; findVars(ValueExpr expr) {<a name="line.216"></a>
<span class="sourceLineNo">217</span>                        vars = new HashSet&lt;String&gt;();<a name="line.217"></a>
<span class="sourceLineNo">218</span>                        expr.visit(this);                       <a name="line.218"></a>
<span class="sourceLineNo">219</span>                        return vars;<a name="line.219"></a>
<span class="sourceLineNo">220</span>                }<a name="line.220"></a>
<span class="sourceLineNo">221</span>                <a name="line.221"></a>
<span class="sourceLineNo">222</span>                <a name="line.222"></a>
<span class="sourceLineNo">223</span>                @Override<a name="line.223"></a>
<span class="sourceLineNo">224</span>                public void meet(Var var) {<a name="line.224"></a>
<span class="sourceLineNo">225</span>                        if (var.getValue()==null)<a name="line.225"></a>
<span class="sourceLineNo">226</span>                                vars.add(var.getName());<a name="line.226"></a>
<span class="sourceLineNo">227</span>                        super.meet(var);<a name="line.227"></a>
<span class="sourceLineNo">228</span>                }<a name="line.228"></a>
<span class="sourceLineNo">229</span>        }<a name="line.229"></a>
<span class="sourceLineNo">230</span>        <a name="line.230"></a>
<span class="sourceLineNo">231</span>        <a name="line.231"></a>
<span class="sourceLineNo">232</span>        protected class FilterExprInsertVisitor extends QueryModelVisitorBase&lt;OptimizationException&gt; {<a name="line.232"></a>
<span class="sourceLineNo">233</span>                <a name="line.233"></a>
<span class="sourceLineNo">234</span>                <a name="line.234"></a>
<span class="sourceLineNo">235</span>                protected boolean canRemove = false;            // if true, the current filter can be removed<a name="line.235"></a>
<span class="sourceLineNo">236</span>                protected FilterExpr filterExpr = null;         // the current filter Expr<a name="line.236"></a>
<span class="sourceLineNo">237</span>                <a name="line.237"></a>
<span class="sourceLineNo">238</span>                <a name="line.238"></a>
<span class="sourceLineNo">239</span>                <a name="line.239"></a>
<span class="sourceLineNo">240</span>                public void initialize(FilterExpr filterExpr) {<a name="line.240"></a>
<span class="sourceLineNo">241</span>                        this.canRemove=true;<a name="line.241"></a>
<span class="sourceLineNo">242</span>                        this.filterExpr = filterExpr;<a name="line.242"></a>
<span class="sourceLineNo">243</span>                }<a name="line.243"></a>
<span class="sourceLineNo">244</span>                <a name="line.244"></a>
<span class="sourceLineNo">245</span>                public boolean canRemove() {<a name="line.245"></a>
<span class="sourceLineNo">246</span>                        return canRemove;<a name="line.246"></a>
<span class="sourceLineNo">247</span>                }<a name="line.247"></a>
<span class="sourceLineNo">248</span>                <a name="line.248"></a>
<span class="sourceLineNo">249</span>                <a name="line.249"></a>
<span class="sourceLineNo">250</span>                @Override<a name="line.250"></a>
<span class="sourceLineNo">251</span>                public void meetOther(QueryModelNode node) {<a name="line.251"></a>
<span class="sourceLineNo">252</span>                        <a name="line.252"></a>
<span class="sourceLineNo">253</span>                        if (node instanceof FilterTuple) {<a name="line.253"></a>
<span class="sourceLineNo">254</span>                                handleFilter((FilterTuple)node, filterExpr);<a name="line.254"></a>
<span class="sourceLineNo">255</span>                        }<a name="line.255"></a>
<span class="sourceLineNo">256</span>                        <a name="line.256"></a>
<span class="sourceLineNo">257</span>                        else if (node instanceof StatementTupleExpr) {<a name="line.257"></a>
<span class="sourceLineNo">258</span>                        <a name="line.258"></a>
<span class="sourceLineNo">259</span>                                // TODO check if we still can remove!!!<a name="line.259"></a>
<span class="sourceLineNo">260</span>                                <a name="line.260"></a>
<span class="sourceLineNo">261</span>                        }<a name="line.261"></a>
<span class="sourceLineNo">262</span>                        <a name="line.262"></a>
<span class="sourceLineNo">263</span>                        else {<a name="line.263"></a>
<span class="sourceLineNo">264</span>                                // TODO we maybe have to adjust canRemove here<a name="line.264"></a>
<span class="sourceLineNo">265</span>                                super.meetOther(node);<a name="line.265"></a>
<span class="sourceLineNo">266</span>                        }<a name="line.266"></a>
<span class="sourceLineNo">267</span>                }<a name="line.267"></a>
<span class="sourceLineNo">268</span>                <a name="line.268"></a>
<span class="sourceLineNo">269</span>                <a name="line.269"></a>
<span class="sourceLineNo">270</span>                private void handleFilter(FilterTuple filterTuple, FilterExpr expr) {<a name="line.270"></a>
<span class="sourceLineNo">271</span>                        <a name="line.271"></a>
<span class="sourceLineNo">272</span>                        /*<a name="line.272"></a>
<span class="sourceLineNo">273</span>                         * CompareEQ expressions are inserted as bindings if possible<a name="line.273"></a>
<span class="sourceLineNo">274</span>                         * <a name="line.274"></a>
<span class="sourceLineNo">275</span>                         * if the filtertuple contains all vars of the filterexpr, we<a name="line.275"></a>
<span class="sourceLineNo">276</span>                         * can evaluate the filter expr safely on the filterTuple<a name="line.276"></a>
<span class="sourceLineNo">277</span>                         * <a name="line.277"></a>
<span class="sourceLineNo">278</span>                         * if there is no intersection of variables, the filter is <a name="line.278"></a>
<span class="sourceLineNo">279</span>                         * irrelevant for this expr<a name="line.279"></a>
<span class="sourceLineNo">280</span>                         * <a name="line.280"></a>
<span class="sourceLineNo">281</span>                         * if there is some intersection, we cannot remove the filter<a name="line.281"></a>
<span class="sourceLineNo">282</span>                         * and have to keep it in the query plan for postfiltering<a name="line.282"></a>
<span class="sourceLineNo">283</span>                         */<a name="line.283"></a>
<span class="sourceLineNo">284</span>                        int intersected = 0;<a name="line.284"></a>
<span class="sourceLineNo">285</span>                        for (String filterVar : expr.getVars()) {<a name="line.285"></a>
<span class="sourceLineNo">286</span>                                if (filterTuple.getFreeVars().contains(filterVar))<a name="line.286"></a>
<span class="sourceLineNo">287</span>                                        intersected++;<a name="line.287"></a>
<span class="sourceLineNo">288</span>                        }<a name="line.288"></a>
<span class="sourceLineNo">289</span>                        <a name="line.289"></a>
<span class="sourceLineNo">290</span>                        // filter expression is irrelevant<a name="line.290"></a>
<span class="sourceLineNo">291</span>                        if (intersected==0)<a name="line.291"></a>
<span class="sourceLineNo">292</span>                                return;<a name="line.292"></a>
<span class="sourceLineNo">293</span>                        <a name="line.293"></a>
<span class="sourceLineNo">294</span>                        // push eq comparison into stmt as bindings<a name="line.294"></a>
<span class="sourceLineNo">295</span>                        if (expr.isCompareEq()) {<a name="line.295"></a>
<span class="sourceLineNo">296</span>                                <a name="line.296"></a>
<span class="sourceLineNo">297</span>                                if (handleCompare(filterTuple, (Compare)expr.getExpression()))<a name="line.297"></a>
<span class="sourceLineNo">298</span>                                        return;<a name="line.298"></a>
<span class="sourceLineNo">299</span>                        }<a name="line.299"></a>
<span class="sourceLineNo">300</span>                        <a name="line.300"></a>
<span class="sourceLineNo">301</span>                        // filter contains all variables =&gt; push filter<a name="line.301"></a>
<span class="sourceLineNo">302</span>                        if (intersected==expr.getVars().size())<a name="line.302"></a>
<span class="sourceLineNo">303</span>                                filterTuple.addFilterExpr(expr);<a name="line.303"></a>
<span class="sourceLineNo">304</span>                        <a name="line.304"></a>
<span class="sourceLineNo">305</span>                        // filter is still needed for post filtering<a name="line.305"></a>
<span class="sourceLineNo">306</span>                        else {<a name="line.306"></a>
<span class="sourceLineNo">307</span>                                canRemove=false;<a name="line.307"></a>
<span class="sourceLineNo">308</span>                        }<a name="line.308"></a>
<span class="sourceLineNo">309</span>                }<a name="line.309"></a>
<span class="sourceLineNo">310</span>                <a name="line.310"></a>
<span class="sourceLineNo">311</span>                <a name="line.311"></a>
<span class="sourceLineNo">312</span>                <a name="line.312"></a>
<span class="sourceLineNo">313</span>                private boolean handleCompare(FilterTuple filterTuple, Compare cmp) {<a name="line.313"></a>
<span class="sourceLineNo">314</span>                        <a name="line.314"></a>
<span class="sourceLineNo">315</span>                        boolean isVarLeft = cmp.getLeftArg() instanceof Var;<a name="line.315"></a>
<span class="sourceLineNo">316</span>                        boolean isVarRight = cmp.getRightArg() instanceof Var;<a name="line.316"></a>
<span class="sourceLineNo">317</span>                        <a name="line.317"></a>
<span class="sourceLineNo">318</span>                        // cases<a name="line.318"></a>
<span class="sourceLineNo">319</span>                        // 1. both vars: we cannot add binding<a name="line.319"></a>
<span class="sourceLineNo">320</span>                        // 2. left var, right value -&gt; add binding<a name="line.320"></a>
<span class="sourceLineNo">321</span>                        // 3. right var, left value -&gt; add binding<a name="line.321"></a>
<span class="sourceLineNo">322</span>                        //<a name="line.322"></a>
<span class="sourceLineNo">323</span>                        // Note: we restrict this optimization to values of type Resource<a name="line.323"></a>
<span class="sourceLineNo">324</span>                        // since for instance subj can only be URIs (i.e. literals are <a name="line.324"></a>
<span class="sourceLineNo">325</span>                        // not allowed). For other types the Filter remains in place.<a name="line.325"></a>
<span class="sourceLineNo">326</span>                        <a name="line.326"></a>
<span class="sourceLineNo">327</span>                        if (isVarLeft &amp;&amp; isVarRight)<a name="line.327"></a>
<span class="sourceLineNo">328</span>                                return false;<a name="line.328"></a>
<span class="sourceLineNo">329</span>                        <a name="line.329"></a>
<span class="sourceLineNo">330</span>                        if (isVarLeft &amp;&amp; cmp.getRightArg() instanceof ValueConstant) {<a name="line.330"></a>
<span class="sourceLineNo">331</span>                                String varName = ((Var)cmp.getLeftArg()).getName();<a name="line.331"></a>
<span class="sourceLineNo">332</span>                                Value value = ((ValueConstant)cmp.getRightArg()).getValue();<a name="line.332"></a>
<span class="sourceLineNo">333</span>                                if (value instanceof Resource) {<a name="line.333"></a>
<span class="sourceLineNo">334</span>                                        filterTuple.addBoundFilter(varName, value);<a name="line.334"></a>
<span class="sourceLineNo">335</span>                                        insertedValues.add(new BindingImpl(varName, value));<a name="line.335"></a>
<span class="sourceLineNo">336</span>                                        return true;<a name="line.336"></a>
<span class="sourceLineNo">337</span>                                }<a name="line.337"></a>
<span class="sourceLineNo">338</span>                        }<a name="line.338"></a>
<span class="sourceLineNo">339</span>                        <a name="line.339"></a>
<span class="sourceLineNo">340</span>                        if (isVarRight &amp;&amp; cmp.getLeftArg() instanceof ValueConstant) {<a name="line.340"></a>
<span class="sourceLineNo">341</span>                                String varName = ((Var)cmp.getRightArg()).getName();<a name="line.341"></a>
<span class="sourceLineNo">342</span>                                Value value = ((ValueConstant)cmp.getLeftArg()).getValue();<a name="line.342"></a>
<span class="sourceLineNo">343</span>                                if (value instanceof Resource) {<a name="line.343"></a>
<span class="sourceLineNo">344</span>                                        filterTuple.addBoundFilter(varName, value);<a name="line.344"></a>
<span class="sourceLineNo">345</span>                                        insertedValues.add(new BindingImpl(varName, value));<a name="line.345"></a>
<span class="sourceLineNo">346</span>                                        return true;<a name="line.346"></a>
<span class="sourceLineNo">347</span>                                }<a name="line.347"></a>
<span class="sourceLineNo">348</span>                        }<a name="line.348"></a>
<span class="sourceLineNo">349</span>                        <a name="line.349"></a>
<span class="sourceLineNo">350</span>                        return false;   // not added<a name="line.350"></a>
<span class="sourceLineNo">351</span>                }<a name="line.351"></a>
<span class="sourceLineNo">352</span>        }<a name="line.352"></a>
<span class="sourceLineNo">353</span>}<a name="line.353"></a>




























































</pre>
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