Copy part 13 to part 14 (unchanged, including Java package).

part-14/build.gradle

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+plugins {
+    id 'antlr'
+    id 'me.champeau.jmh' version '0.6.6'
+}
+
+dependencies {
+    antlr "org.antlr:antlr4:$antlr_version"
+    implementation "org.graalvm.js:js:$graal_version"
+    implementation "org.graalvm.tools:profiler:$graal_version"
+    implementation "org.apache.commons:commons-text:1.10.0"
+}
+
+// required to allow GraalVM to discover our EasyScript language class
+test {
+    jvmArgs '-Dgraalvm.locatorDisabled=true'
+}

part-14/src/jmh/java/com/endoflineblog/truffle/part_13/CounterThisBenchmark.java

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+package com.endoflineblog.truffle.part_13;
+
+import org.openjdk.jmh.annotations.Benchmark;
+
+/**
+ * A benchmark measuring the performance of storing state inside class instances.
+ */
+public class CounterThisBenchmark extends TruffleBenchmark {
+    private static final int INPUT = 1_000_000;
+
+    private static final String COUNTER_CLASS = "" +
+            "class CounterDirect { " +
+            "    constructor() { " +
+            "        this.count = 0; " +
+            "    } " +
+            "    increment() { " +
+            "        this.count = this.count + 1; " +
+            "    } " +
+            "    getCount() { " +
+            "        return this.count; " +
+            "    } " +
+            "} " +
+            "class CounterIndexed { " +
+            "    constructor() { " +
+            "        this['count'] = 0; " +
+            "    } " +
+            "    increment() { " +
+            "        this['count'] = this['count'] + 1; " +
+            "    } " +
+            "    getCount() { " +
+            "        return this['count']; " +
+            "    } " +
+            "}";
+
+    @Override
+    public void setup() {
+        super.setup();
+
+        this.truffleContext.eval("ezs", COUNTER_CLASS);
+        this.truffleContext.eval("ezs", COUNT_WITH_THIS_IN_FOR);
+
+        this.truffleContext.eval("js", COUNTER_CLASS);
+        this.truffleContext.eval("js", COUNT_WITH_THIS_IN_FOR);
+    }
+
+    private static final String COUNT_WITH_THIS_IN_FOR = "" +
+            "function countWithThisInForDirect(n) { " +
+            "    const counter = new CounterDirect(); " +
+            "    for (let i = 0; i < n; i = i + 1) { " +
+            "        counter.increment(); " +
+            "    } " +
+            "    return counter.getCount(); " +
+            "} " +
+            "function countWithThisInForIndexed(n) { " +
+            "    const counter = new CounterIndexed(); " +
+            "    for (let i = 0; i < n; i = i + 1) { " +
+            "        counter['increment'](); " +
+            "    } " +
+            "    return counter['getCount'](); " +
+            "}";
+
+    @Benchmark
+    public int count_with_this_in_for_direct_ezs() {
+        return this.truffleContext.eval("ezs", "countWithThisInForDirect(" + INPUT + ");").asInt();
+    }
+
+    @Benchmark
+    public int count_with_this_in_for_direct_js() {
+        return this.truffleContext.eval("js", "countWithThisInForDirect(" + INPUT + ");").asInt();
+    }
+
+    @Benchmark
+    public int count_with_this_in_for_indexed_ezs() {
+        return this.truffleContext.eval("ezs", "countWithThisInForIndexed(" + INPUT + ");").asInt();
+    }
+
+    @Benchmark
+    public int count_with_this_in_for_indexed_js() {
+        return this.truffleContext.eval("js", "countWithThisInForIndexed(" + INPUT + ");").asInt();
+    }
+}

part-14/src/jmh/java/com/endoflineblog/truffle/part_13/TruffleBenchmark.java

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+package com.endoflineblog.truffle.part_13;
+
+import org.graalvm.polyglot.Context;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.TearDown;
+import org.openjdk.jmh.annotations.Warmup;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * The common superclass of all JMH benchmarks.
+ * Identical to the class with the same name from part 12.
+ */
+@Warmup(iterations = 5, time = 1)
+@Measurement(iterations = 5, time = 1)
+@Fork(value = 1, jvmArgsAppend = {
+        "-Dgraalvm.locatorDisabled=true",
+        "--add-exports",
+        "org.graalvm.truffle/com.oracle.truffle.api.staticobject=ALL-UNNAMED"
+})
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MICROSECONDS)
+@State(Scope.Benchmark)
+public abstract class TruffleBenchmark {
+    protected Context truffleContext;
+
+    @Setup
+    public void setup() {
+        this.truffleContext = Context.create();
+    }
+
+    @TearDown
+    public void tearDown() {
+        this.truffleContext.close();
+    }
+}

part-14/src/main/antlr/com/endoflineblog/truffle/part_13/parsing/antlr/EasyScript.g4

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+grammar EasyScript ;
+
+@header{
+package com.endoflineblog.truffle.part_13.parsing.antlr;
+}
+
+start : stmt+ EOF ;
+
+stmt :         kind=('var' | 'let' | 'const') binding (',' binding)* ';'? #VarDeclStmt
+     |                                                         expr1 ';'? #ExprStmt
+     |                                    'function' subroutine_decl ';'? #FuncDeclStmt
+     |                                               'return' expr1? ';'? #ReturnStmt
+     |                                                 '{' stmt* '}' ';'? #BlockStmt
+     |    'if' '(' cond=expr1 ')' then_stmt=stmt ('else' else_stmt=stmt)? #IfStmt
+     |                               'while' '(' cond=expr1 ')' body=stmt #WhileStmt
+     |                 'do' '{' stmt* '}' 'while' '(' cond=expr1 ')' ';'? #DoWhileStmt
+     | 'for' '(' init=stmt? ';' cond=expr1? ';' updt=expr1? ')' body=stmt #ForStmt
+     |                                                       'break' ';'? #BreakStmt
+     |                                                    'continue' ';'? #ContinueStmt
+     |                              'class' ID '{' class_member* '}' ';'? #ClassDeclStmt
+     ;
+binding : ID ('=' expr1)? ;
+class_member : subroutine_decl ;
+subroutine_decl : name=ID '(' args=func_args ')' '{' stmt* '}' ;
+func_args : (ID (',' ID)* )? ;
+
+expr1 : ID '=' expr1                                       #AssignmentExpr1
+      | object=expr5 '.' ID '=' rvalue=expr1               #PropertyWriteExpr1
+      | arr=expr5 '[' index=expr1 ']' '=' rvalue=expr1     #ArrayIndexWriteExpr1
+      | expr2                                              #PrecedenceTwoExpr1
+      ;
+expr2 : left=expr2 c=('===' | '!==') right=expr3           #EqNotEqExpr2
+      | expr3                                              #PrecedenceThreeExpr2
+      ;
+expr3 : left=expr3 c=('<' | '<=' | '>' | '>=') right=expr4 #ComparisonExpr3
+      | expr4                                              #PrecedenceFourExpr3
+      ;
+expr4 : left=expr4 o=('+' | '-') right=expr5               #AddSubtractExpr4
+      | '-' expr5                                          #UnaryMinusExpr4
+      | expr5                                              #PrecedenceFiveExpr4
+      ;
+expr5 : expr5 '.' ID                                       #PropertyReadExpr5
+      | arr=expr5 '[' index=expr1 ']'                      #ArrayIndexReadExpr5
+      | expr5 '(' (expr1 (',' expr1)*)? ')'                #CallExpr5
+      | expr6                                              #PrecedenceSixExpr5
+      ;
+expr6 : literal                                            #LiteralExpr6
+      | 'this'                                             #ThisExpr6
+      | ID                                                 #ReferenceExpr6
+      | '[' (expr1 (',' expr1)*)? ']'                      #ArrayLiteralExpr6
+      | 'new' constr=expr6 ('('(expr1 (',' expr1)*)?')')?  #NewExpr6
+      | '(' expr1 ')'                                      #PrecedenceOneExpr6
+      ;
+
+literal : INT | DOUBLE | 'undefined' | bool_literal | string_literal ;
+bool_literal : 'true' | 'false' ;
+
+fragment DIGIT : [0-9] ;
+INT : DIGIT+ ;
+DOUBLE : DIGIT+ '.' DIGIT+ ;
+
+fragment LETTER : [a-zA-Z$_] ;
+ID : LETTER (LETTER | DIGIT)* ;
+
+string_literal: SINGLE_QUOTE_STRING | DOUBLE_QUOTE_STRING ;
+// see https://stackoverflow.com/questions/24557953/handling-string-literals-which-end-in-an-escaped-quote-in-antlr4
+// for details
+SINGLE_QUOTE_STRING : '\'' (~[\\'\r\n] | '\\' ~[\r\n])* '\'' ;
+DOUBLE_QUOTE_STRING : '"'  (~[\\"\r\n] | '\\' ~[\r\n])* '"' ;
+
+// skip all whitespace
+WS : (' ' | '\r' | '\t' | '\n' | '\f')+ -> skip ;

part-14/src/main/java/com/endoflineblog/truffle/part_13/EasyScriptLanguageContext.java

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+package com.endoflineblog.truffle.part_13;
+
+import com.endoflineblog.truffle.part_13.common.ShapesAndPrototypes;
+import com.oracle.truffle.api.TruffleLanguage;
+import com.oracle.truffle.api.nodes.Node;
+import com.oracle.truffle.api.object.DynamicObject;
+
+/**
+ * The class of the context for the
+ * {@link EasyScriptTruffleLanguage TruffleLanguage implementaton in this part of the series}.
+ * Very similar to the class with the same name from part 12,
+ * the only difference being that the {@link ShapesAndPrototypes}
+ * object is now accessible from here, instead of just the string prototype.
+ */
+public final class EasyScriptLanguageContext {
+    private static final TruffleLanguage.ContextReference<EasyScriptLanguageContext> REF =
+            TruffleLanguage.ContextReference.create(EasyScriptTruffleLanguage.class);
+
+    /** Retrieve the current language context for the given {@link Node}. */
+    public static EasyScriptLanguageContext get(Node node) {
+        return REF.get(node);
+    }
+
+    public final DynamicObject globalScopeObject;
+
+    /**
+     * The object containing the shapes and prototypes,
+     * both for user-defined class instances, and for built-in objects.
+     */
+    public final ShapesAndPrototypes shapesAndPrototypes;
+
+    public EasyScriptLanguageContext(DynamicObject globalScopeObject, ShapesAndPrototypes shapesAndPrototypes) {
+        this.globalScopeObject = globalScopeObject;
+        this.shapesAndPrototypes = shapesAndPrototypes;
+    }
+}