语法解析器续:case..when表达式计算
之前写过一篇博客,是关于如何解析类似sql之类的解析器实现参考:https://www.cnblogs.com/yougewe/p/13774289.html
之前的解析器,更多的是是做语言的翻译转换工作,并不涉及具体的数据运算。而且抛弃了许多上下文关联语法处理,所以相对还是简单的。
那么,如果我们想做一下数据运算呢?比如我给你一些值,然后给你一个表达式,你可以给出其运算结果吗?
1:表达式运算难度如何?
比如,已知表达式为, field1 > 0 and field2 > 0, 然后已知道值 field1 = 1, field2 = 2; 那么,此运算结果必当为true。这很理所当然!
但以上,仅为人工处理,自己用大脑做了下运算,得到结果。如果转换为代码,又当如何?
我想,我们至少要做这么几件事:
    1. 解析出所有字段有field1, field2;
    2. 解析出比较运算符 >;
    3. 解析出右边具体的比较值;
    4. 解析出连接运算符and;
    5. 做所有的比较运算;
    6. 关联优先级得到最终结果;
怎么样?现在还觉得很简单吗?如果是,请收下我的膝盖!
但是,如果真要做这种泛化的场景,那就相当相当复杂了,要知道类似于HIVE之类的重量级产品,语法解析都是其中重要的组成部分。实际上,这可能涉及到相当多的语言规范需要做了。所以,必然超出我们的简化理解范围。
所以,我这里仅挑一个简单场景做解析:即如题所说,case..when..的解析。
所以,我们可以范围缩减为,给定表达式:case when field1 > 0 then 'f1' else 'fn' end; 的判断解析。比如给定值 field1=1, 则应得到结果 f1, 如果给定值 field1=0, 则应得到结果 fn.
在划定范围之后,好像更有了目标感了。但是问题真的简单了吗?实际上,还是有相当多的分支需要处理的,因为case..when..中可以嵌套其他语法。所以,我们只能尽力而为了。
2. case..when..表达式运算的实现
命题确立之后,我们可以开始着手如何实现了。如上描述,我们有两个已知条件:表达式和基础值。
基于上一篇文章的解析,我们基本可以快速得到所有组成case when 的元素token信息了。这就为我们省去了不少事。这里,我着重给一个如何获取整个case..when..词句的实现,使其可形成一个独立的词组。
// 将case..when.. 归结为sql类关键词的实现中public SqlKeywordAstHandler(TokenDescriptor masterToken,Iterator<TokenDescriptor> candidates,TokenTypeEnum tokenType) {super(masterToken, candidates, tokenType);String word = masterToken.getRawWord().toLowerCase();if("case".equals(word)) {completeCaseWhenTokens(candidates);}}/*** 实例case...when... 词汇列表** @param candidates 待用词汇*/private void completeCaseWhenTokens(Iterator<TokenDescriptor> candidates) {boolean syntaxClosed = false;while (candidates.hasNext()) {TokenDescriptor token = candidates.next();addExtendToken(token);if("end".equalsIgnoreCase(token.getRawWord())) {syntaxClosed = true;break;}}if(!syntaxClosed) {throw new SyntaxException("语法错误:case..when..未闭合");}}
以上,就是获取case..when..词组的方法了,主要就是从case开始,到end结束,中间的所有词根,都被划作其范围。当然,还有一个重要的点,是将数据字段找出来,放到可取到的地方。
有了一个个独立的元素,我们就可以进行语义分析了。该分析可以放在该解析器中,但也许并不会太通用,所以,此处我将其抽象为一个单独的值运算类。在需要的地方,再实例化该运算类,即可。核心问题如上一节中描述,具体实现代码如下:
import com.my.mvc.app.common.exception.SyntaxException;import com.my.mvc.app.common.helper.parser.SyntaxStatement;import com.my.mvc.app.common.helper.parser.TokenDescriptor;import com.my.mvc.app.common.helper.parser.TokenTypeEnum;import lombok.extern.slf4j.Slf4j;import org.apache.commons.lang3.StringUtils;import java.math.BigDecimal;import java.util.*;import java.util.stream.Collectors;/*** 功能描述: case..when.. 真实数据运算帮助类**/@Slf4jpublic class CaseWhenElDataCalcHelper {/*** case when 完整语法*/private SyntaxStatement caseWhenStmt;public CaseWhenElDataCalcHelper(SyntaxStatement caseWhenStmt) {this.caseWhenStmt = caseWhenStmt;}/*** 计算case..when的结果** @param suppliers 原始所有值* @return 最终计算出的值*/public String calcCaseWhenData(Map<String, String> suppliers) {List<TokenDescriptor> allTokens = caseWhenStmt.getAllTokens();TokenDescriptor masterToken = allTokens.get(0);if(!"case".equalsIgnoreCase(masterToken.getRawWord())) {throw new SyntaxException("不是case..when..表达式");}int tokenLen = allTokens.size();if(tokenLen < 3) {throw new SyntaxException("case..when..表达式语法错误");}TokenDescriptor closureToken = allTokens.get(tokenLen - 1);if(!"end".equalsIgnoreCase(closureToken.getRawWord())) {throw new SyntaxException("case..when..表达式未闭合");}// 暂只支持 case when xxx then xxx... end 语法// 不支持 case field_name when 1 then '1'... end, 即单字段判定不支持List<TokenDescriptor> whenExpressionCandidates;for (int i = 1; i < tokenLen - 1; i++) {whenExpressionCandidates = new ArrayList<>();TokenDescriptor currentToken = allTokens.get(i);if("when".equalsIgnoreCase(currentToken.getRawWord())) {// 需走各分支逻辑while (i + 1 < tokenLen) {TokenDescriptor nextToken = allTokens.get(i + 1);if("then".equalsIgnoreCase(nextToken.getRawWord())) {break;}whenExpressionCandidates.add(nextToken);++i;}if(judgeWhenExpression(whenExpressionCandidates, suppliers)) {List<TokenDescriptor> resultCandidates= scrapeCaseWhenResultCandidates(allTokens, i + 1);return calcExpressionData(resultCandidates, suppliers);}// 直接进入下一轮迭代,then后面为空迭代}if("else".equalsIgnoreCase(currentToken.getRawWord())) {List<TokenDescriptor> resultCandidates= scrapeCaseWhenResultCandidates(allTokens, i);return calcExpressionData(resultCandidates, suppliers);}}return null;}/*** 捞出所有的结果运算token列表** @param allTokens 全局token表* @param start 偏移量* @return 获取到的所有结果运算token*/private List<TokenDescriptor> scrapeCaseWhenResultCandidates(List<TokenDescriptor> allTokens,int start) {List<TokenDescriptor> resultCandidates = new ArrayList<>();while (start + 1 < allTokens.size()) {TokenDescriptor nextToken = allTokens.get(start + 1);String word = nextToken.getRawWord();if("when".equalsIgnoreCase(word)|| "else".equalsIgnoreCase(word)|| "end".equalsIgnoreCase(word)) {break;}resultCandidates.add(nextToken);++start;}return resultCandidates;}/*** 判断when条件是否成立** @param operatorCandidates 可供运算的表达式token列表* @param suppliers 原始字段取值来源* @return true:符合该判定,false:判定失败*/private boolean judgeWhenExpression(List<TokenDescriptor> operatorCandidates,Map<String, String> suppliers) {List<AndOrOperatorSupervisor> supervisors= partitionByPriority(operatorCandidates);Boolean prevJudgeSuccess = null;for (AndOrOperatorSupervisor calc1 : supervisors) {Map<String, List<TokenDescriptor>> unitGroup = calc1.getUnitGroupTokens();String op = unitGroup.get("OP").get(0).getRawWord();if(calc1.getPrevType() != null&& prevJudgeSuccess != null && !prevJudgeSuccess) {// 上一个and运算为false, 本次直接为falseif("and".equalsIgnoreCase(calc1.getPrevType().getRawWord())) {continue;}}String leftValue = calcExpressionData(unitGroup.get("LEFT"), suppliers);TokenTypeEnum resultType = getPriorDataTypeByTokenList(unitGroup.get("RIGHT"));boolean myJudgeSuccess;if("in".equals(op)) {myJudgeSuccess = checkExistsIn(leftValue, unitGroup.get("RIGHT"), resultType);}else if("notin".equals(op)) {myJudgeSuccess = !checkExistsIn(leftValue, unitGroup.get("RIGHT"), resultType);}else {String rightValue = calcExpressionData(unitGroup.get("RIGHT"), suppliers);myJudgeSuccess = checkCompareTrue(leftValue, op,rightValue, resultType);}TokenDescriptor prevType = calc1.getPrevType();TokenDescriptor nextType = calc1.getNextType();// 单条件判定if(prevType == null && nextType == null) {return myJudgeSuccess;}if(nextType == null) {return myJudgeSuccess;}prevJudgeSuccess = myJudgeSuccess;if("and".equalsIgnoreCase(nextType.getRawWord())) {if(!myJudgeSuccess&& calc1.getNeedMoreStepsAfterMyFail() <= 0) {return false;}continue;}if("or".equalsIgnoreCase(nextType.getRawWord())) {if(myJudgeSuccess) {return true;}continue;}log.warn("解析到未知的next连接判定符:{}", nextType);throw new SyntaxException("语法解析错误");}log.warn("未判定出结果,使用默认返回,请检查");return false;}/*** 根据值信息推断运算数据类型** @param tokenList 结果列表(待运算)* @return 计算的数据类型,数字或字符串*/private TokenTypeEnum getPriorDataTypeByTokenList(List<TokenDescriptor> tokenList) {for (TokenDescriptor token : tokenList) {if(token.getTokenType() == TokenTypeEnum.WORD_STRING) {return TokenTypeEnum.WORD_STRING;}}return TokenTypeEnum.WORD_NUMBER;}/*** 运算返回具体的 判定值** @param resultCandidates 结果表达式token列表* @param suppliers 原始字段取值来源* @return true:符合该判定,false:判定失败*/private String calcExpressionData(List<TokenDescriptor> resultCandidates,Map<String, String> suppliers) {// 暂时假设结果中不再提供运算处理TokenDescriptor first = resultCandidates.get(0);if(first.getTokenType() == TokenTypeEnum.WORD_NORMAL) {if("null".equalsIgnoreCase(first.getRawWord())) {return null;}return suppliers.get(first.getRawWord());}return unwrapStringToken(first.getRawWord());}/*** 判断给定值是否在列表中** @param aValue 要判定的值* @param itemList 范围表* @return true:成立, false:不在其中*/private boolean checkExistsIn(String aValue,List<TokenDescriptor> itemList,TokenTypeEnum valueType) {if(aValue == null) {return false;}BigDecimal aValueNumber = null;for (TokenDescriptor tk1 : itemList) {if(valueType == TokenTypeEnum.WORD_NUMBER) {if(aValueNumber == null) {aValueNumber = new BigDecimal(aValue);}if(aValueNumber.compareTo(new BigDecimal(tk1.getRawWord())) == 0) {return true;}continue;}if(aValue.equals(unwrapStringToken(tk1.getRawWord()))) {return true;}}return false;}/*** 将字符串两边的引号去除,保持字符串属性** @param wrappedStr 含引号的字符串,如 'abc',"abc"* @return abc 无引号包裹的字符串*/private String unwrapStringToken(String wrappedStr) {if(wrappedStr == null || wrappedStr.length() == 0) {return null;}char[] values = wrappedStr.toCharArray();int i = 0;while (i < values.length - 1&& (values[i] == '"' || values[i] == '\'')) {i++;}int j = values.length - 1;while (j > 0&& (values[j] == '"' || values[j] == '\'')) {j--;}return new String(values, i, j - i + 1);}/*** 比较两个值ab是否基于op成立** @param aValue 左值* @param op 比较运算符* @param bValue 右值* @param valueType 值类型, 主要是区分数字与字符* @return 是否等式成立, true:成立, false:不成立*/private boolean checkCompareTrue(String aValue,String op,String bValue,TokenTypeEnum valueType) {// 首先进行相生性判定if("null".equals(bValue)) {bValue = null;}switch(op) {case "=":if(bValue == null) {return aValue == null;}return bValue.equals(aValue);case "!=":case "<>":if(bValue == null) {return aValue != null;}return !bValue.equals(aValue);}if(bValue == null) {log.warn("非null值不能用比较符号运算");throw new SyntaxException("语法错误");}// >=,<=,>,< 判定int compareResult = compareTwoData(aValue, bValue, valueType);switch(op) {case ">":return compareResult > 0;case ">=":return compareResult >= 0;case "<=":return compareResult <= 0;case "<":return compareResult < 0;}throw new SyntaxException("未知的运算符");}// 比较两个值大小abprivate int compareTwoData(String aValue,String bValue,TokenTypeEnum tokenType) {bValue = unwrapStringToken(bValue);if(bValue == null) {// 按任意值大于null 规则处理return aValue == null ? 0 : 1;}// 被比较值为null, 则按小于计算if(aValue == null) {return -1;}if(tokenType == TokenTypeEnum.WORD_NUMBER) {return new BigDecimal(aValue).compareTo(new BigDecimal(bValue));}return aValue.compareTo(unwrapStringToken(bValue));}// 将token重新分组,以便可以做原子运算private List<AndOrOperatorSupervisor> partitionByPriority(List<TokenDescriptor> tokens) {// 1. 取左等式token列表// 2. 取等式表达式// 3. 取右等式token列表// 4. 构建一个表达式,做最小分组// 5. 检查是否有下一运算符,如有则必定为and|or|(// 6. 保存上一连接判定符,新开一个分组// 7. 重复步骤1-6,直到取完所有token// 前置运算符,决定是否要运算本节点,以及结果的合并方式// 比如 and, 则当前点必须参与运算,如果前节点结果为false,则直接返回false// 否则先计算本节点TokenDescriptor preType = null;// 当前节点计算完成后,判断下一运算是否有必要触发// 为and时则当前为true时必须触发,为or时当前为false触发TokenDescriptor nextType = null;// key 为 left, op, right, 各value为细分tksMap<String, List<TokenDescriptor>> unitGroup = new HashMap<>();String currentReadPos = "LEFT";List<TokenDescriptor> smallGroupTokenList = new ArrayList<>();// 以上为描述单个运算的字符,使用一个list就可以描述无括号的表达式了List<AndOrOperatorSupervisor> bracketGroup = new ArrayList<>();AndOrOperatorSupervisor supervisor= new AndOrOperatorSupervisor(null, unitGroup);bracketGroup.add(supervisor);for (int i = 0; i < tokens.size(); i++) {TokenDescriptor token = tokens.get(i);String word = token.getRawWord().toLowerCase();TokenTypeEnum tokenType = token.getTokenType();// 忽略分隔符,假设只有一级运算,忽略空格带来的复杂优先级问题if(tokenType == TokenTypeEnum.CLAUSE_SEPARATOR) {continue;}// 字段直接判定if(tokenType == TokenTypeEnum.COMPARE_OPERATOR&& !",".equals(word)) {unitGroup.put("OP", Collections.singletonList(token));currentReadPos = "RIGHT";continue;}// is null, is not null 解析if("is".equals(word)) {while (i + 1 < tokens.size()) {TokenDescriptor nextToken = tokens.get(i + 1);if("null".equalsIgnoreCase(nextToken.getRawWord())) {TokenDescriptor opToken = new TokenDescriptor("=",TokenTypeEnum.COMPARE_OPERATOR);unitGroup.put("OP", Collections.singletonList(opToken));currentReadPos = "RIGHT";List<TokenDescriptor> curTokenList = unitGroup.computeIfAbsent(currentReadPos, r -> new ArrayList<>());curTokenList.add(nextToken);// 跳过1个tokeni += 1;break;}if("not".equalsIgnoreCase(nextToken.getRawWord())) {if(i + 2 >= tokens.size()) {throw new SyntaxException("语法错误3: is");}nextToken = tokens.get(i + 2);if(!"null".equalsIgnoreCase(nextToken.getRawWord())) {throw new SyntaxException("语法错误4: is");}TokenDescriptor opToken = new TokenDescriptor("!=",TokenTypeEnum.COMPARE_OPERATOR);unitGroup.put("OP", Collections.singletonList(opToken));currentReadPos = "RIGHT";List<TokenDescriptor> curTokenList = unitGroup.computeIfAbsent(currentReadPos, r -> new ArrayList<>());curTokenList.add(nextToken);// 跳过2个tokeni += 2;break;}}continue;}// in (x,x,xx) 语法解析if("in".equals(word)) {TokenDescriptor opToken = new TokenDescriptor("in",TokenTypeEnum.COMPARE_OPERATOR);unitGroup.put("OP", Collections.singletonList(opToken));currentReadPos = "RIGHT";List<TokenDescriptor> curTokenList = unitGroup.computeIfAbsent(currentReadPos, r -> new ArrayList<>());i = parseInItems(tokens, curTokenList, i);continue;}// not in (x,xxx,xx) 语法解析if("not".equals(word)) {if(i + 1 > tokens.size()) {throw new SyntaxException("语法错误:not");}TokenDescriptor nextToken = tokens.get(i + 1);// 暂不支持 not exists 等语法if(!"in".equalsIgnoreCase(nextToken.getRawWord())) {throw new SyntaxException("不支持的语法:not");}TokenDescriptor opToken = new TokenDescriptor("notin",TokenTypeEnum.COMPARE_OPERATOR);unitGroup.put("OP", Collections.singletonList(opToken));currentReadPos = "RIGHT";List<TokenDescriptor> curTokenList = unitGroup.computeIfAbsent(currentReadPos, r -> new ArrayList<>());i = parseInItems(tokens, curTokenList, i + 1);continue;}// 暂只解析一级,无括号情况if("and".equals(word)|| "or".equals(word)) {supervisor.setNextType(token);// 滚动到下一运算分支unitGroup = new HashMap<>();supervisor = new AndOrOperatorSupervisor(token, unitGroup);bracketGroup.add(supervisor);currentReadPos = "LEFT";continue;}List<TokenDescriptor> curTokenList = unitGroup.computeIfAbsent(currentReadPos, r -> new ArrayList<>());curTokenList.add(token);}sortAndSetCalcFlag(bracketGroup);return bracketGroup;}/*** 按优先级重排序或其他工作** @param bracketGroup 按先后排序的原子运算*/private void sortAndSetCalcFlag(List<AndOrOperatorSupervisor> bracketGroup) {for (int i = bracketGroup.size() - 1; i > 0; i--) {AndOrOperatorSupervisor calc1 = bracketGroup.get(i);TokenDescriptor prevUnionDesc = calc1.getPrevType();if(prevUnionDesc == null) {continue;}if(!"or".equalsIgnoreCase(prevUnionDesc.getRawWord())) {continue;}// 增加当前节点失败后的重试次数for (int j = 0; j < i; j++) {AndOrOperatorSupervisor calcTemp = bracketGroup.get(j);calcTemp.incrStepAfterMyFail();}}}/*** 解析in中的所有元素到结果中** @param tokens 所有token* @param curTokenList 当前结果表* @param start in 开始的地方* @return in 语法结束位置*/private int parseInItems(List<TokenDescriptor> tokens,List<TokenDescriptor> curTokenList,int start) {while (start + 1 < tokens.size()) {TokenDescriptor nextToken = tokens.get(++start);String nextWord = nextToken.getRawWord();if("(".equals(nextWord)|| ",".equals(nextWord)) {// in 开始continue;}if(")".equals(nextWord)) {break;}curTokenList.add(nextToken);}return start;}/*** 最小运算单元描述符*/private class AndOrOperatorSupervisor {// 前置运算符,决定是否要运算本节点,以及结果的合并方式// 比如 and, 则当前点必须参与运算,如果前节点结果为false,则直接返回false// 否则先计算本节点private TokenDescriptor prevType;// 当前节点计算完成后,判断下一运算是否有必要触发// 为and时则当前为true时必须触发,为or时当前为false触发private TokenDescriptor nextType;// key 为 left, op, right, 各value为细分tksprivate Map<String, List<TokenDescriptor>> unitGroupTokens;/*** 当当前节点运算失败后,还需要尝试的更多运算数量(如 or 运算)*/private int needMoreStepsAfterMyFail;public AndOrOperatorSupervisor(TokenDescriptor prevType,Map<String, List<TokenDescriptor>> unitGroupTokens) {this.prevType = prevType;this.unitGroupTokens = unitGroupTokens;}public void setNextType(TokenDescriptor nextType) {this.nextType = nextType;}public TokenDescriptor getPrevType() {return prevType;}public TokenDescriptor getNextType() {return nextType;}public Map<String, List<TokenDescriptor>> getUnitGroupTokens() {return unitGroupTokens;}public int getNeedMoreStepsAfterMyFail() {return needMoreStepsAfterMyFail;}public void incrStepAfterMyFail() {this.needMoreStepsAfterMyFail++;}@Overridepublic String toString() {return StringUtils.join(unitGroupTokens.get("LEFT").stream().map(TokenDescriptor::getRawWord).collect(Collectors.toList()), ' ')+ unitGroupTokens.get("OP").get(0).getRawWord()+StringUtils.join(unitGroupTokens.get("RIGHT").stream().map(TokenDescriptor::getRawWord).collect(Collectors.toList()), ' ') +", prev=" + prevType+ ", next=" + nextType;}}}
每使用时,传入case..when..的语句构造出一个新的计算实例,然后调用 calcCaseWhenData(rawData), 带入已知参数信息,即可运算出最终的case..when..值。
为使处理简单起见,这里并没有深入各种逻辑嵌套处理,直接忽略掉括号的处理了。另外,对于数值类的运算也暂时被忽略,如 field1 > 1+1 这种运算,并不会计算出2来。这些东西,需要的同学,完全可以稍加完善,即可支持处理这些逻辑。
对于null值的处理,此处遵循null值小于任意值,任意值大于null值的约定。类型区分字符型与数值型,以右值为类型推断依据。即不允许将数值型值写为字符串型,除非两者可以得到同样的结果。非数值型字段,不得用于数学运算。(尽管以上实现并未处理数值运算)
因 case when 的语法还是比较清晰的,所以我们只是做了顺序地读取,判定即得出结果。另外对于 case when 的单值判定并不支持,所以实现并不复杂。但这完全不影响我们理解整个语法处理的思想。相信需要的同学定能有所启发。
3. 表达式计算单元测试
以上仅实现代码,需要附加上各种场景测试,才算可以work的东西。主要就是针对种 and/or, in, is null 等的处理。如下:
import com.my.mvc.app.common.helper.CaseWhenElDataCalcHelper;import com.my.mvc.app.common.helper.SimpleSyntaxParser;import com.my.mvc.app.common.helper.parser.ParsedClauseAst;import lombok.extern.slf4j.Slf4j;import org.junit.Assert;import org.junit.Test;import java.util.HashMap;import java.util.Map;@Slf4jpublic class CaseWhenElDataCalcHelperTest {@Testpublic void testCaseWhenSimple1() {String condition;ParsedClauseAst parsedClause;CaseWhenElDataCalcHelper helper;Map<String, String> rawData;condition = "case \n" +"\twhen (kehu_phone is null or field1 != 'c') then m_phone \n" +"\telse kehu_phone\n" +"end";parsedClause = SimpleSyntaxParser.parse(condition);helper = new CaseWhenElDataCalcHelper(parsedClause.getAst().get(0));rawData = new HashMap<>();rawData.put("kehu_phone", "kehu_phone_v1");rawData.put("field1", "field1_v");rawData.put("m_phone", "m_phone_v");Assert.assertEquals("case..when..中解析字段信息不正确",3, parsedClause.getIdMapping().size());Assert.assertEquals("case..when..解析结果错误",rawData.get("m_phone"),helper.calcCaseWhenData(rawData));condition = "case \n" +"\twhen (kehu_phone is null) then m_phone \n" +"\telse kehu_phone\n" +"end";parsedClause = SimpleSyntaxParser.parse(condition);helper = new CaseWhenElDataCalcHelper(parsedClause.getAst().get(0));rawData = new HashMap<>();rawData.put("kehu_phone", "kehu_phone_v1");rawData.put("field1", "field1_v");rawData.put("m_phone", "m_phone_v");Assert.assertEquals("case..when..中解析字段信息不正确",2, parsedClause.getIdMapping().size());Assert.assertEquals("case..when..解析结果错误",rawData.get("kehu_phone"),helper.calcCaseWhenData(rawData));rawData.remove("kehu_phone");Assert.assertEquals("case..when..解析结果错误",rawData.get("m_phone"),helper.calcCaseWhenData(rawData));condition = " case \n" +" \twhen is_sx_emp='Y' then 'Y1' \n" +" \twhen is_sx_new_custom!='Y' then 'Y2' \n" +" \twhen is_sx_fort_promot_custom='Y' then 'Y3' \n" +" \twhen promotion_role_chn in ('10','11') and first_tenthousand_dt is not null then 'Y4' \n" +" \telse 'N' \n" +" end";parsedClause = SimpleSyntaxParser.parse(condition);helper = new CaseWhenElDataCalcHelper(parsedClause.getAst().get(0));rawData = new HashMap<>();rawData.put("is_sx_emp", "N");rawData.put("is_sx_new_custom", "Y");rawData.put("is_sx_fortune_promot_custom", "N");rawData.put("promotion_role_chn", "10");rawData.put("first_tenthousand_dt", "10");Assert.assertEquals("case..when..中解析字段信息不正确",5, parsedClause.getIdMapping().size());Assert.assertEquals("case..when..in解析结果错误","Y4",helper.calcCaseWhenData(rawData));rawData = new HashMap<>();rawData.put("is_sx_emp", "N");rawData.put("is_sx_new_custom", "Y");rawData.put("is_sx_fortune_promot_custom", "N");rawData.put("first_tenthousand_dt", "10");rawData.put("promotion_role_chn", "9");Assert.assertEquals("case..when..else解析结果错误","N",helper.calcCaseWhenData(rawData));rawData = new HashMap<>();rawData.put("is_sx_new_custom", "Y");rawData.put("is_sx_fortune_promot_custom", "N");rawData.put("first_tenthousand_dt", "10");rawData.put("promotion_role_chn", "9");rawData.put("is_sx_emp", "Y");Assert.assertEquals("case..when..=解析结果错误","Y1",helper.calcCaseWhenData(rawData));rawData = new HashMap<>();rawData.put("is_sx_emp", "N");rawData.put("is_sx_new_custom", "N");rawData.put("is_sx_fortune_promot_custom", "N");rawData.put("first_tenthousand_dt", "10");rawData.put("promotion_role_chn", "9");Assert.assertEquals("case..when..!=解析结果错误","Y2",helper.calcCaseWhenData(rawData));rawData = new HashMap<>();rawData.put("is_sx_emp", "N");rawData.put("is_sx_new_custom", "Y");rawData.put("is_sx_fortune_promot_custom", "N");// rawData.put("first_tenthousand_dt", "10");rawData.put("promotion_role_chn", "11.1");Assert.assertEquals("case..when..in+and+null解析结果错误","N",helper.calcCaseWhenData(rawData));condition = " case \n" +" \twhen is_sx_emp='Y' then 'Y1' \n" +" \twhen or_emp != null or or_emp2 > 3 then 'Y2_OR' \n" +" \twhen and_emp != null and and_emp2 > 3 or or_tmp3 <= 11 then 'Y3_OR' \n" +" \twhen promotion_role_chn not in ('10','11') and first_tenthousand_dt is not null then 'Y4' \n" +" \twhen promotion_role_chn not in ('10') then 'Y5_NOTIN' \n" +" \telse 'N_ELSE' \n" +" end";parsedClause = SimpleSyntaxParser.parse(condition);helper = new CaseWhenElDataCalcHelper(parsedClause.getAst().get(0));rawData = new HashMap<>();rawData.put("is_sx_emp", "N");rawData.put("or_emp", "Y");Assert.assertEquals("case..when..中解析字段信息不正确",8, parsedClause.getIdMapping().size());Assert.assertEquals("case..when..in解析结果错误","Y2_OR",helper.calcCaseWhenData(rawData));rawData = new HashMap<>();rawData.put("is_sx_emp", "N");// rawData.put("or_emp", "Y");rawData.put("or_emp2", "2");rawData.put("or_tmp3", "12");Assert.assertEquals("case..when..or>2解析结果错误","Y5_NOTIN",helper.calcCaseWhenData(rawData));rawData = new HashMap<>();rawData.put("is_sx_emp", "N");// rawData.put("or_emp", "Y");rawData.put("or_emp2", "2");rawData.put("or_tmp3", "13");rawData.put("promotion_role_chn", "10");Assert.assertEquals("case..when..notin解析结果错误","N_ELSE",helper.calcCaseWhenData(rawData));condition = " case \n" +" \twhen (is_sx_emp='Y' or a_field=3) then 'Y1' \n" +" \telse 'N_ELSE' \n" +" end";parsedClause = SimpleSyntaxParser.parse(condition);helper = new CaseWhenElDataCalcHelper(parsedClause.getAst().get(0));rawData = new HashMap<>();rawData.put("is_sx_emp", "N");rawData.put("or_emp", "Y");Assert.assertEquals("case..when..中解析字段信息不正确",2, parsedClause.getIdMapping().size());Assert.assertEquals("case..when..()号解析结果错误","N_ELSE",helper.calcCaseWhenData(rawData));rawData = new HashMap<>();rawData.put("is_sx_emp", "Y");rawData.put("or_emp", "Y");Assert.assertEquals("case..when..中解析字段信息不正确",2, parsedClause.getIdMapping().size());Assert.assertEquals("case..when..()号解析结果错误2","Y1",helper.calcCaseWhenData(rawData));condition = " case \n" +" \twhen (field1 != '0' and field2 != '0' or field3 != '0') then field3 \n" +" \telse 'N_ELSE' \n" +" end";parsedClause = SimpleSyntaxParser.parse(condition);helper = new CaseWhenElDataCalcHelper(parsedClause.getAst().get(0));rawData = new HashMap<>();rawData.put("field1", "f1");rawData.put("field2", "f2");rawData.put("field3", "f3");Assert.assertEquals("case..when..中解析字段信息不正确",3, parsedClause.getIdMapping().size());Assert.assertEquals("case..when..and+or优先级解析结果错误",rawData.get("field3"),helper.calcCaseWhenData(rawData));rawData = new HashMap<>();rawData.put("field1", "0");rawData.put("field2", "f2");rawData.put("field3", "f3");Assert.assertEquals("case..when..and+or优先级解析结果错误",rawData.get("field3"),helper.calcCaseWhenData(rawData));}}
如果有更多场景,我们只需添加测试,然后完善相应逻辑即可。这里所有的测试,都可以基于sql协议进行,如有空缺则应弥补相应功能,而非要求用户按自己的标准来,毕竟标准是个好东西。
4. 更多表达式计算
实际上,对表达式计算这东西,我们也许不一定非要自己去实现。毕竟太费力。有开源产品支持的,比如:aviator: https://www.oschina.net/p/aviator?hmsr=aladdin1e1 https://www.jianshu.com/p/02403dd1f4c4
如果该语法不支持,则可以先转换成支持的语法,再使用其引擎计算即可。
表达式计算,看起来像是在做了计算的工作,然而本质上,也都是在做翻译工作,只不过它是将表达式翻译成了java语言执行而已!

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