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borismarinborismarin
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‎.gitignore

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*.*~
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target
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src/main/java/META-INF/MANIFEST.MF
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.DS_Store
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*.class
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# Package Files #
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*.jar
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*.war
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*.ear
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# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
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hs_err_pid*
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/.settings/

‎.project

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<?xml version="1.0" encoding="UTF-8"?>
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<projectDescription>
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<name>lems-expr-parser</name>
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<comment></comment>
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<projects>
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</projects>
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<buildSpec>
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<buildCommand>
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<name>org.eclipse.xtext.ui.shared.xtextBuilder</name>
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<arguments>
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</arguments>
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</buildCommand>
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<buildCommand>
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<name>org.eclipse.jdt.core.javabuilder</name>
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<arguments>
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</arguments>
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</buildCommand>
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<buildCommand>
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<name>org.eclipse.m2e.core.maven2Builder</name>
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<arguments>
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</arguments>
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</buildCommand>
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</buildSpec>
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<natures>
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<nature>org.eclipse.jdt.core.javanature</nature>
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<nature>org.eclipse.m2e.core.maven2Nature</nature>
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<nature>org.eclipse.xtext.ui.shared.xtextNature</nature>
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</natures>
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</projectDescription>

‎pom.xml

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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
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http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<groupId>org.lemsml.model</groupId>
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<artifactId>lems-expr-parser</artifactId>
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<version>0.0-SNAPSHOT</version>
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<packaging>jar</packaging>
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<dependencies>
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<dependency>
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<groupId>org.antlr</groupId>
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<artifactId>antlr4-maven-plugin</artifactId>
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<version>4.3</version>
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</dependency>
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<dependency>
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<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.11</version>
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<scope>test</scope>
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<type>jar</type>
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</dependency>
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</dependencies>
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<properties>
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<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
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</properties>
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<build>
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<plugins>
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<plugin>
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<groupId>org.eclipse.m2e</groupId>
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<artifactId>lifecycle-mapping</artifactId>
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<version>1.0.0</version>
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<configuration>
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<lifecycleMappingMetadata>
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<pluginExecutions>
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<pluginExecution>
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<pluginExecutionFilter>
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<groupId>org.antlr</groupId>
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<artifactId>antlr4-maven-plugin</artifactId>
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<versionRange>[4.1,)</versionRange>
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<goals>
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<goal>antlr4</goal>
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</goals>
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</pluginExecutionFilter>
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<action>
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<execute>
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<runOnIncremental>true</runOnIncremental>
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</execute>
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</action>
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</pluginExecution>
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</pluginExecutions>
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</lifecycleMappingMetadata>
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</configuration>
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</plugin>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-compiler-plugin</artifactId>
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<version>3.1</version>
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<configuration>
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<source>1.7</source>
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<target>1.7</target>
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</configuration>
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</plugin>
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<plugin>
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<groupId>org.codehaus.mojo</groupId>
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<artifactId>exec-maven-plugin</artifactId>
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<version>1.2.1</version>
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<executions>
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<execution>
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<goals>
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<goal>java</goal>
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</goals>
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</execution>
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</executions>
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<configuration>
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<mainClass>Run</mainClass>
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</configuration>
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</plugin>
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<plugin>
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<groupId>org.antlr</groupId>
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<artifactId>antlr4-maven-plugin</artifactId>
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<version>4.1</version>
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<configuration>
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<listener>false</listener>
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<visitor>true</visitor>
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</configuration>
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<executions>
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<execution>
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<goals>
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<goal>antlr4</goal>
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</goals>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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</project>
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‎src/main/antlr4/CommonLexerRules.g4

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lexer grammar CommonLexerRules;
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NEWLINE: '\r' ? '\n' ; // return newlines to parser (end-statement signal)
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ID : [a-zA-Z]+ ; // match identifiers
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WS : [ \t]+ -> skip ; // toss out whitespace
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MUL : '*' ;
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DIV : '/' ;
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ADD : '+' ;
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SUB : '-' ;
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POW : '^' ;
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FLOAT: DIGIT+ '.' DIGIT* EXP? [Ll]?
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| DIGIT+ EXP? [Ll]?
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| '.' DIGIT+ EXP? [Ll]?
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;
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fragment
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DIGIT: '0'..'9' ;
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fragment
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EXP : ('E' | 'e') ('+' | '-')? DIGIT+ ;
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‎src/main/antlr4/LEMSExpression.g4

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grammar LEMSExpression;
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import CommonLexerRules;
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base: expr
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;
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expr: '(' expr ')' # parens
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| BuiltinFuncs '(' expr? ')' # funcCall
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| '-' expr # Negate
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| expr op=POW expr # Pow
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| expr op=(MUL | DIV) expr # MulDiv
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| expr op=(ADD | SUB) expr # AddSub
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| FLOAT # float
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| ID # id
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;
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BuiltinFuncs: 'sin'
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| 'cos'
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| 'tan'
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;

‎src/main/java/EvalVisitor.java

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public class EvalVisitor extends LEMSExpressionBaseVisitor<Float> {
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/** expr */
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@Override
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public Float visitBase(LEMSExpressionParser.BaseContext ctx) {
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Float result = visit(ctx.expr());
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System.out.println(ctx.expr().getText() + " = " + result);
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return result;
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}
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/** '-' expr */
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@Override
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public Float visitNegate(LEMSExpressionParser.NegateContext ctx) {
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return -visit(ctx.expr());
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}
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/** expr op=POW expr */
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@Override
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public Float visitPow(LEMSExpressionParser.PowContext ctx) {
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Float left = visit(ctx.expr(0)); // get value of left subexpression
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Float right = visit(ctx.expr(1)); // get value of right subexpression
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return new Float(Math.pow(left, right));
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}
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/** FLOAT */
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@Override
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public Float visitFloat(LEMSExpressionParser.FloatContext ctx) {
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return Float.valueOf(ctx.FLOAT().getText());
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}
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/** expr op=('*'|'/') expr */
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@Override
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public Float visitMulDiv(LEMSExpressionParser.MulDivContext ctx) {
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Float left = visit(ctx.expr(0)); // get value of left subexpression
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Float right = visit(ctx.expr(1)); // get value of right subexpression
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if (ctx.op.getType() == LEMSExpressionParser.MUL)
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return left * right;
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return left / right; // must be DIV
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}
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/** expr op=('+'|'-') expr */
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@Override
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public Float visitAddSub(LEMSExpressionParser.AddSubContext ctx) {
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Float left = visit(ctx.expr(0)); // get value of left subexpression
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Float right = visit(ctx.expr(1)); // get value of right subexpression
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if (ctx.op.getType() == LEMSExpressionParser.ADD)
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return left + right;
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return left - right; // must be SUB
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}
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/** '(' expr ')' */
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@Override
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public Float visitParens(LEMSExpressionParser.ParensContext ctx) {
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return visit(ctx.expr()); // return child expr's value
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}
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/** BuiltinFuncs '(' expr ')' */
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@Override
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public Float visitFuncCall(LEMSExpressionParser.FuncCallContext ctx) {
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Float ret = null;
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switch (ctx.BuiltinFuncs().getText()) {
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case "sin":
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ret = new Float(Math.sin(visit(ctx.expr())));
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break;
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case "cos":
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ret = new Float(Math.cos(visit(ctx.expr())));
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break;
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case "tan":
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ret = new Float(Math.tan(visit(ctx.expr())));
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break;
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}
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return ret;
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}
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}

‎src/test/java/EvalVisitorTest.java

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import static org.junit.Assert.assertEquals;
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import org.antlr.v4.runtime.ANTLRInputStream;
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import org.antlr.v4.runtime.CommonTokenStream;
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import org.antlr.v4.runtime.tree.ParseTree;
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import org.junit.Test;
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public class EvalVisitorTest {
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private static final double EPSILON = 0.0000000001d;
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@Test
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public void testAddSub() {
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assertEquals(2.0d, getResult("1.5 + 0.5"), EPSILON);
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assertEquals(1.0d, getResult("1.5 - 0.5"), EPSILON);
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}
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@Test
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public void testMultDiv() {
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assertEquals(-6.0d, getResult("-0.2e1 * 3"), EPSILON);
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assertEquals(3.0d, getResult("9 / 3"), EPSILON);
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}
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@Test
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public void testParenthesis() {
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assertEquals(4.5d, getResult("3 * (1 + .5)"), EPSILON);
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}
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@Test
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public void testNegate() {
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assertEquals(1.5d, getResult("3 * (1 + -.5)"), EPSILON);
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}
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@Test
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public void testTwoParenthesis() {
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assertEquals(4.5d, getResult("3 * ((9.0 - 7) / 2 + .5)"), EPSILON);
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}
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@Test
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public void testTrig() {
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assertEquals(0.0d, getResult("sin(0)"), EPSILON);
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assertEquals(1.0d, getResult("sin(0.5*3.14159265359)"), EPSILON);
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assertEquals(1.0d, getResult("sin(1/2)^2 + cos(1/2)^2"), EPSILON);
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}
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private Float getResult(String expression) {
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ANTLRInputStream input = new ANTLRInputStream(expression);
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LEMSExpressionLexer lexer = new LEMSExpressionLexer(input);
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CommonTokenStream tokens = new CommonTokenStream(lexer);
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LEMSExpressionParser parser = new LEMSExpressionParser(tokens);
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ParseTree tree = parser.base();
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EvalVisitor eval = new EvalVisitor();
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return eval.visit(tree);
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}
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}

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