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add StringBuilderGen to the gizmo2 module
This is a simple generator of `StringBuilder` call chains. It exists outside of Gizmo because of unresolved disputes over its API design, particularly around reusability.
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‎gizmo2/pom.xml‎

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<artifactId>junit-jupiter</artifactId>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>io.quarkus.gizmo</groupId>
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<artifactId>gizmo2</artifactId>
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<type>test-jar</type>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<build>

‎gizmo2/src/main/java/org/jboss/jandex/gizmo2/StringBuilderGen.java‎

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package org.jboss.jandex.gizmo2;
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import io.quarkus.gizmo2.Const;
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import io.quarkus.gizmo2.Expr;
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import io.quarkus.gizmo2.Var;
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import io.quarkus.gizmo2.creator.BlockCreator;
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import io.quarkus.gizmo2.creator.ops.ComparableOps;
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import io.quarkus.gizmo2.creator.ops.ObjectOps;
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/**
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* Generator of {@link StringBuilder} call chains. The expected usage pattern is:
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* <ol>
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* <li>Create an instance using {@link #ofNew(BlockCreator)}</li>
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* <li>Append to it using {@link #append(Expr)}</li>
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* <li>Create the final string using {@link #toString_()}</li>
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* </ol>
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* If you need to perform other operations on the {@code StringBuilder}
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* that this class doesn't provide, you should create an instance
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* using {@link #of(Var, BlockCreator)}, which allows passing an already
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* created {@code StringBuilder}. This class itself doesn't provide access
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* to the underlying object.
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*/
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public final class StringBuilderGen extends ObjectOps implements ComparableOps {
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/**
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* Allocates a local variable in the given block as if by {@code new StringBuilder()}
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* and passes it to {@link #of(Var, BlockCreator)}.
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*
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* @param bc the block in which the new {@code StringBuilder} should be created
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* @return the result of {@link #of(Var, BlockCreator)} called on the new {@code StringBuilder}
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*/
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public static StringBuilderGen ofNew(BlockCreator bc) {
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return new StringBuilderGen(bc, bc.localVar("$$stringBuilder", bc.new_(StringBuilder.class)));
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}
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/**
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* Allocates a local variable in the given block as if by {@code new StringBuilder(capacity)}
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* and passes it to {@link #of(Var, BlockCreator)}.
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*
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* @param bc the block in which the new {@code StringBuilder} should be created
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* @return the result of {@link #of(Var, BlockCreator)} called on the new {@code StringBuilder}
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*/
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public static StringBuilderGen ofNew(int capacity, BlockCreator bc) {
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return new StringBuilderGen(bc, bc.localVar("$$stringBuilder", bc.new_(StringBuilder.class, Const.of(capacity))));
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}
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/**
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* Creates a {@code StringBuilder} generator that helps to generate a chain of
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* {@code append} calls and a final {@code toString} call.
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*
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* <pre>
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* StringBuilderGen str = StringBuilderGen.of(theStringBuilder, bc);
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* str.append("constant");
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* str.append(someExpr);
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* Expr result = str.toString_();
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* </pre>
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*
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* The {@code append} method mimics the regular {@code StringBuilder.append}, so
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* it accepts {@code Expr}s of all types for which {@code StringBuilder}
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* has an overload:
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* <ul>
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* <li>primitive types</li>
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* <li>{@code char[]}</li>
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* <li>{@code java.lang.String}</li>
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* <li>{@code java.lang.CharSequence}</li>
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* <li>{@code java.lang.Object}</li>
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* </ul>
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*
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* Notably, arrays except of {@code char[]} are appended using {@code Object.toString}
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* and if {@code Arrays.toString} should be used, it must be generated manually
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* (see {@link BlockCreator#arrayToString(Expr)}).
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* <p>
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* Methods for appending only a part of {@code char[]} or {@code CharSequence} are not
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* provided.
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* <p>
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* Note that the returned instance <em>may be reused</em> to append to the same {@code StringBuilder}
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* in the same {@code BlockCreator} multiple times. This allows using {@code StringBuilderGen}
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* in the same manner a {@code StringBuilder} would normally be used.
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*
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* @param stringBuilder the {@link StringBuilder}
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* @param bc the {@link BlockCreator}
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* @return a convenience wrapper for accessing instance methods of the given {@link StringBuilder}
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*/
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public static StringBuilderGen of(Var stringBuilder, BlockCreator bc) {
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return new StringBuilderGen(bc, stringBuilder);
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}
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private StringBuilderGen(final BlockCreator bc, final Var obj) {
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super(StringBuilder.class, bc, obj);
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}
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/**
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* Appends the string value of given {@code expr} to this {@code StringBuilder}.
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*
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* @param expr the value to append
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* @return this instance
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*/
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public StringBuilderGen append(final Expr expr) {
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switch (expr.type().descriptorString()) {
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case "Z" -> invokeInstance(StringBuilder.class, "append", boolean.class, expr);
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case "B", "S", "I" -> invokeInstance(StringBuilder.class, "append", int.class, expr);
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case "J" -> invokeInstance(StringBuilder.class, "append", long.class, expr);
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case "F" -> invokeInstance(StringBuilder.class, "append", float.class, expr);
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case "D" -> invokeInstance(StringBuilder.class, "append", double.class, expr);
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case "C" -> invokeInstance(StringBuilder.class, "append", char.class, expr);
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case "[C" -> invokeInstance(StringBuilder.class, "append", char[].class, expr);
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case "Ljava/lang/String;" -> invokeInstance(StringBuilder.class, "append", String.class, expr);
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case "Ljava/lang/CharSequence;" -> invokeInstance(StringBuilder.class, "append", CharSequence.class, expr);
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default -> invokeInstance(StringBuilder.class, "append", Object.class, expr);
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}
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return this;
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}
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/**
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* Appends the given {@code char} constant to this {@code StringBuilder}.
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*
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* @param constant the value to append
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* @return this instance
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*/
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public StringBuilderGen append(final char constant) {
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return append(Const.of(constant));
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}
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/**
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* Appends the given {@code String} constant to this {@code StringBuilder}.
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*
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* @param constant the value to append
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* @return this instance
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*/
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public StringBuilderGen append(final String constant) {
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return append(Const.of(constant));
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}
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/**
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* Appends the given code point to this {@code StringBuilder}.
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*
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* @param codePoint the value to append (must not be {@code null})
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* @return this instance
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*/
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public StringBuilderGen appendCodePoint(final Expr codePoint) {
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invokeInstance(StringBuilder.class, "appendCodePoint", int.class, codePoint);
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return this;
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}
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/**
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* Appends the given code point to this {@code StringBuilder}.
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*
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* @param codePoint the value to append
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* @return this instance
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*/
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public StringBuilderGen appendCodePoint(final int codePoint) {
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return appendCodePoint(Const.of(codePoint));
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}
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/**
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* Set the length of this {@code StringBuilder}.
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*
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* @param length the length expression (must not be {@code null})
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*/
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public void setLength(Expr length) {
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invokeInstance(void.class, "setLength", int.class, length);
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}
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/**
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* Set the length of this {@code StringBuilder}.
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*
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* @param length the constant length
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*/
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public void setLength(int length) {
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setLength(Const.of(length));
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}
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@Override
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public Expr compareTo(Expr other) {
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return invokeInstance(int.class, "compareTo", StringBuilder.class, other);
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}
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}

‎gizmo2/src/test/java/org/jboss/jandex/gizmo2/StringBuilderGenTest.java‎

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package org.jboss.jandex.gizmo2;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import java.util.function.Supplier;
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import org.junit.jupiter.api.Test;
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import io.quarkus.gizmo2.Const;
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import io.quarkus.gizmo2.Gizmo;
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import io.quarkus.gizmo2.LocalVar;
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import io.quarkus.gizmo2.TestClassMaker;
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import io.quarkus.gizmo2.desc.MethodDesc;
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public class StringBuilderGenTest {
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@Test
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public void testStringBuilder() {
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TestClassMaker tcm = new TestClassMaker();
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Gizmo g = Gizmo.create(tcm);
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g.class_("io.quarkus.gizmo2.TestStringBuilder", cc -> {
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MethodDesc charSeq = cc.staticMethod("createCharSequence", mc -> {
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mc.returning(CharSequence.class);
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mc.body(bc -> {
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LocalVar strBuilder = bc.localVar("stringBuilder", bc.new_(StringBuilder.class));
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StringBuilderGen.of(strBuilder, bc).append("ghi");
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bc.return_(strBuilder);
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});
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});
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cc.staticMethod("createString", mc -> {
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mc.returning(Object.class); // in fact always `String`
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mc.body(bc -> {
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bc.return_(StringBuilderGen.ofNew(bc)
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.append(Const.of(true))
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.append(Const.of((byte) 1))
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.append(Const.of((short) 2))
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.append(Const.of(3))
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.append(Const.of(4L))
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.append(Const.of(5.0F))
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.append(Const.of(6.0))
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.append(Const.of('a'))
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.append(bc.newArray(char.class, Const.of('b'), Const.of('c')))
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.append(Const.of("def"))
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.append(bc.invokeStatic(charSeq))
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.append(bc.new_(MyObject.class))
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.append(Const.ofNull(Object.class))
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.append("...")
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.append('!')
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.toString_());
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});
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});
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});
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assertEquals("true12345.06.0abcdefghijklmnull...!", tcm.staticMethod("createString", Supplier.class).get());
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}
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public static class MyObject {
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@Override
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public String toString() {
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return "jklm";
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}
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}
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@Test
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public void testStringBuilderWithControlFlow() {
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TestClassMaker tcm = new TestClassMaker();
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Gizmo g = Gizmo.create(tcm);
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g.class_("io.quarkus.gizmo2.TestStringBuilder", cc -> {
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cc.staticMethod("createString", mc -> {
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mc.returning(Object.class); // always `String`
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mc.body(b0 -> {
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LocalVar msg = b0.localVar("msg", b0.new_(StringBuilder.class));
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StringBuilderGen msgBuilder = StringBuilderGen.of(msg, b0).append("FooBar");
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LocalVar i = b0.localVar("i", Const.of(0));
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b0.while_(b1 -> b1.yield(b1.lt(i, 5)), b1 -> {
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StringBuilderGen.of(msg, b1).append("Baz").append(i);
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b1.inc(i);
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});
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msgBuilder.append("Quux");
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b0.return_(msgBuilder.toString_());
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});
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});
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});
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assertEquals("FooBarBaz0Baz1Baz2Baz3Baz4Quux", tcm.staticMethod("createString", Supplier.class).get());
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}
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}

‎pom.xml‎

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<artifactId>gizmo2</artifactId>
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<version>${version.gizmo2}</version>
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</dependency>
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<dependency>
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<groupId>io.quarkus.gizmo</groupId>
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<artifactId>gizmo2</artifactId>
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<type>test-jar</type>
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<version>${version.gizmo2}</version>
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</dependency>
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<dependency>
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<groupId>net.bytebuddy</groupId>
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<artifactId>byte-buddy</artifactId>

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