Java tutorial
/************************************************************************************** * Copyright (C) 2006-2015 EsperTech Inc. All rights reserved. * * http://www.espertech.com/esper * * http://www.espertech.com * * ---------------------------------------------------------------------------------- * * The software in this package is published under the terms of the GPL license * * a copy of which has been included with this distribution in the license.txt file. * **************************************************************************************/ package com.espertech.esper.epl.parse; import com.espertech.esper.epl.expression.core.ExprEvaluatorContext; import com.espertech.esper.epl.expression.core.ExprNode; import com.espertech.esper.epl.expression.time.ExprTimePeriod; import com.espertech.esper.epl.generated.EsperEPL2GrammarParser; import com.espertech.esper.epl.spec.*; import com.espertech.esper.epl.variable.VariableService; import com.espertech.esper.schedule.TimeProvider; import org.antlr.v4.runtime.CommonTokenStream; import org.antlr.v4.runtime.Token; import org.antlr.v4.runtime.tree.Tree; import java.util.List; import java.util.Map; /** * Builds an output limit spec from an output limit AST node. */ public class ASTOutputLimitHelper { /** * Build an output limit spec from the AST node supplied. * * @param astExprNodeMap is the map of current AST tree nodes to their respective expression root node * @param engineURI the engine uri * @param timeProvider provides time * @param variableService provides variable resolution * @param exprEvaluatorContext context for expression evaluatiom * @return output limit spec */ public static OutputLimitSpec buildOutputLimitSpec(CommonTokenStream tokenStream, EsperEPL2GrammarParser.OutputLimitContext ctx, Map<Tree, ExprNode> astExprNodeMap, VariableService variableService, String engineURI, TimeProvider timeProvider, ExprEvaluatorContext exprEvaluatorContext) { OutputLimitLimitType displayLimit = OutputLimitLimitType.DEFAULT; if (ctx.k != null) { switch (ctx.k.getType()) { case EsperEPL2GrammarParser.FIRST: displayLimit = OutputLimitLimitType.FIRST; break; case EsperEPL2GrammarParser.LAST: displayLimit = OutputLimitLimitType.LAST; break; case EsperEPL2GrammarParser.SNAPSHOT: displayLimit = OutputLimitLimitType.SNAPSHOT; break; case EsperEPL2GrammarParser.ALL: displayLimit = OutputLimitLimitType.ALL; break; default: throw ASTWalkException.from("Encountered unrecognized token " + ctx.k.getText(), tokenStream, ctx); } } // next is a variable, or time period, or number String variableName = null; Double rate = null; ExprNode whenExpression = null; List<ExprNode> crontabScheduleSpec = null; List<OnTriggerSetAssignment> thenExpressions = null; ExprTimePeriod timePeriodExpr = null; OutputLimitRateType rateType; ExprNode andAfterTerminateExpr = null; List<OnTriggerSetAssignment> andAfterTerminateSetExpressions = null; if (ctx.t != null) { rateType = OutputLimitRateType.TERM; if (ctx.expression() != null) { andAfterTerminateExpr = ASTExprHelper.exprCollectSubNodes(ctx.expression(), 0, astExprNodeMap) .get(0); } if (ctx.onSetExpr() != null) { andAfterTerminateSetExpressions = ASTExprHelper .getOnTriggerSetAssignments(ctx.onSetExpr().onSetAssignmentList(), astExprNodeMap); } } else if (ctx.wh != null) { rateType = OutputLimitRateType.WHEN_EXPRESSION; whenExpression = ASTExprHelper.exprCollectSubNodes(ctx.expression(), 0, astExprNodeMap).get(0); if (ctx.onSetExpr() != null) { thenExpressions = ASTExprHelper.getOnTriggerSetAssignments(ctx.onSetExpr().onSetAssignmentList(), astExprNodeMap); } } else if (ctx.at != null) { rateType = OutputLimitRateType.CRONTAB; crontabScheduleSpec = ASTExprHelper.exprCollectSubNodes(ctx.crontabLimitParameterSet(), 0, astExprNodeMap); } else { if (ctx.ev != null) { rateType = ctx.e != null ? OutputLimitRateType.EVENTS : OutputLimitRateType.TIME_PERIOD; if (ctx.i != null) { variableName = ctx.i.getText(); } else if (ctx.timePeriod() != null) { timePeriodExpr = (ExprTimePeriod) ASTExprHelper .exprCollectSubNodes(ctx.timePeriod(), 0, astExprNodeMap).get(0); } else { ASTExprHelper.exprCollectSubNodes(ctx.number(), 0, astExprNodeMap); // remove rate = Double.parseDouble(ctx.number().getText()); } } else { rateType = OutputLimitRateType.AFTER; } } // get the AFTER time period ExprTimePeriod afterTimePeriodExpr = null; Integer afterNumberOfEvents = null; if (ctx.outputLimitAfter() != null) { if (ctx.outputLimitAfter().timePeriod() != null) { ExprNode expression = ASTExprHelper.exprCollectSubNodes(ctx.outputLimitAfter(), 0, astExprNodeMap) .get(0); afterTimePeriodExpr = (ExprTimePeriod) expression; } else { Object constant = ASTConstantHelper.parse(ctx.outputLimitAfter().number()); afterNumberOfEvents = ((Number) constant).intValue(); } } boolean andAfterTerminate = false; if (ctx.outputLimitAndTerm() != null) { andAfterTerminate = true; if (ctx.outputLimitAndTerm().expression() != null) { andAfterTerminateExpr = ASTExprHelper .exprCollectSubNodes(ctx.outputLimitAndTerm().expression(), 0, astExprNodeMap).get(0); } if (ctx.outputLimitAndTerm().onSetExpr() != null) { andAfterTerminateSetExpressions = ASTExprHelper.getOnTriggerSetAssignments( ctx.outputLimitAndTerm().onSetExpr().onSetAssignmentList(), astExprNodeMap); } } return new OutputLimitSpec(rate, variableName, rateType, displayLimit, whenExpression, thenExpressions, crontabScheduleSpec, timePeriodExpr, afterTimePeriodExpr, afterNumberOfEvents, andAfterTerminate, andAfterTerminateExpr, andAfterTerminateSetExpressions); } /** * Builds a row limit specification. * @return row limit spec */ public static RowLimitSpec buildRowLimitSpec(EsperEPL2GrammarParser.RowLimitContext ctx) { Object numRows; Object offset; if (ctx.o != null) { // format "rows offset offsetcount" numRows = parseNumOrVariableIdent(ctx.n1, ctx.i1); offset = parseNumOrVariableIdent(ctx.n2, ctx.i2); } else if (ctx.c != null) { // format "offsetcount, rows" offset = parseNumOrVariableIdent(ctx.n1, ctx.i1); numRows = parseNumOrVariableIdent(ctx.n2, ctx.i2); } else { numRows = parseNumOrVariableIdent(ctx.n1, ctx.i1); offset = null; } Integer numRowsInt = null; String numRowsVariable = null; if (numRows instanceof String) { numRowsVariable = (String) numRows; } else { numRowsInt = (Integer) numRows; } Integer offsetInt = null; String offsetVariable = null; if (offset instanceof String) { offsetVariable = (String) offset; } else { offsetInt = (Integer) offset; } return new RowLimitSpec(numRowsInt, offsetInt, numRowsVariable, offsetVariable); } private static Object parseNumOrVariableIdent(EsperEPL2GrammarParser.NumberconstantContext num, Token ident) { if (ident != null) { return ident.getText(); } else { return ASTConstantHelper.parse(num); } } }