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Ashley Frieze
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BAEL-3905 - replacing tokens tests and implementation
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‎core-java-modules/core-java-regex/pom.xml‎

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<artifactId>jmh-generator-annprocess</artifactId>
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<version>${jmh-core.version}</version>
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</dependency>
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<dependency>
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<groupId>org.assertj</groupId>
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<artifactId>assertj-core</artifactId>
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<version>3.15.0</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<build>

‎core-java-modules/core-java-regex/src/main/java/com/baeldung/replacetokens/ReplacingTokens.java‎

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package com.baeldung.replacetokens;
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import java.util.function.Function;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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public class ReplacingTokens {
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public static final Pattern TITLE_CASE_PATTERN = Pattern.compile("(?<=^|[^A-Za-z])([A-Z][a-z]*)(?=[^A-Za-z]|$)");
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/**
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* Iterate over the title case tokens in the input and replace them with lowercase
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* @param original the original string
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* @return a string with words replaced with their lowercase equivalents
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*/
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public static String replaceTitleCaseWithLowerCase(String original) {
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int lastIndex = 0;
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StringBuilder output = new StringBuilder();
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Matcher matcher = TITLE_CASE_PATTERN.matcher(original);
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while (matcher.find()) {
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output.append(original, lastIndex, matcher.start())
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.append(convert(matcher.group(1)));
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lastIndex = matcher.end();
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}
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if (lastIndex < original.length()) {
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output.append(original, lastIndex, original.length());
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}
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return output.toString();
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}
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/**
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* Convert a token found into its desired lowercase
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* @param token the token to convert
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* @return the converted token
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*/
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private static String convert(String token) {
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return token.toLowerCase();
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}
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/**
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* Replace all the tokens in an input using the algorithm provided for each
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* @param original original string
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* @param tokenPattern the pattern to match with
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* @param converter the conversion to apply
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* @return the substituted string
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*/
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public static String replaceTokens(String original, Pattern tokenPattern,
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Function<Matcher, String> converter) {
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int lastIndex = 0;
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StringBuilder output = new StringBuilder();
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Matcher matcher = tokenPattern.matcher(original);
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while (matcher.find()) {
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output.append(original, lastIndex, matcher.start())
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.append(converter.apply(matcher));
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lastIndex = matcher.end();
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}
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if (lastIndex < original.length()) {
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output.append(original, lastIndex, original.length());
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}
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return output.toString();
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}
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}

‎core-java-modules/core-java-regex/src/test/java/com/baeldung/replacetokens/ReplacingTokensUnitTest.java‎

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package com.baeldung.replacetokens;
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import org.junit.Test;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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import static com.baeldung.replacetokens.ReplacingTokens.TITLE_CASE_PATTERN;
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import static com.baeldung.replacetokens.ReplacingTokens.replaceTokens;
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import static org.assertj.core.api.Assertions.assertThat;
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public class ReplacingTokensUnitTest {
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private static final String EXAMPLE_INPUT = "First 3 Capital Words! then 10 TLAs, I Found";
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private static final String EXAMPLE_INPUT_PROCESSED = "first 3 capital words! then 10 TLAs, i found";
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@Test
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public void whenFindMatches_thenTitleWordsFound() {
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Matcher matcher = TITLE_CASE_PATTERN.matcher(EXAMPLE_INPUT);
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List<String> matches = new ArrayList<>();
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while (matcher.find()) {
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matches.add(matcher.group(1));
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}
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assertThat(matches)
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.containsExactly("First", "Capital", "Words", "I", "Found");
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}
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@Test
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public void exploreMatches() {
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Matcher matcher = TITLE_CASE_PATTERN.matcher(EXAMPLE_INPUT);
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while (matcher.find()) {
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System.out.println("Match: " + matcher.group(0));
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System.out.println("Start: " + matcher.start());
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System.out.println("End: " + matcher.end());
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}
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}
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@Test
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public void whenReplaceTokensWithLowerCase() {
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assertThat(ReplacingTokens.replaceTitleCaseWithLowerCase(EXAMPLE_INPUT))
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.isEqualTo(EXAMPLE_INPUT_PROCESSED);
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}
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@Test
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public void whenReplaceTokensWithLowerCaseUsingGeneralPurpose() {
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assertThat(replaceTokens("First 3 Capital Words! then 10 TLAs, I Found",
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TITLE_CASE_PATTERN,
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match -> match.group(1).toLowerCase()))
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.isEqualTo("first 3 capital words! then 10 TLAs, i found");
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}
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@Test
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public void escapeRegexCharacters() {
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Pattern regexCharacters = Pattern.compile("[<(\\[{\\\\^\\-=$!|\\]})?*+.>]");
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assertThat(replaceTokens("A regex character like [",
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regexCharacters,
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match -> "\\" + match.group()))
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.isEqualTo("A regex character like \\[");
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}
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@Test
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public void replacePlaceholders() {
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Pattern placeholderPattern = Pattern.compile("\\$\\{(?<placeholder>[A-Za-z0-9-_]+)}");
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Map<String, String> placeholderValues = new HashMap<>();
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placeholderValues.put("name", "Bill");
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placeholderValues.put("company", "Baeldung");
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assertThat(replaceTokens("Hi ${name} at ${company}",
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placeholderPattern,
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match -> placeholderValues.get(match.group("placeholder"))))
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.isEqualTo("Hi Bill at Baeldung");
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}
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}

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