Add hashcode support to ConfigurationPropertyName

Provide a hashcode implementation for `ConfigurationPropertyName` so
that instances can be stored in Map without them all ending up in the
same bucket.

See gh-20625

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyName.java

@@ -64,6 +64,8 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 
 	private String string;
 
+	private int hashCode;
+
 	private ConfigurationPropertyName(Elements elements) {
 		this.elements = elements;
 		this.uniformElements = new CharSequence[elements.getSize()];
@@ -322,23 +324,39 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 		}
 	}
 
-	private boolean defaultElementEquals(Elements e1, Elements e2, int i) {
+	private boolean fastElementEquals(Elements e1, Elements e2, int i) {
+		int length1 = e1.getLength(i);
+		int length2 = e2.getLength(i);
+		if (length1 == length2) {
+			int i1 = 0;
+			while (length1-- != 0) {
+				char ch1 = e1.charAt(i, i1);
+				char ch2 = e2.charAt(i, i1);
+				if (ch1 != ch2) {
+					return false;
+				}
+				i1++;
+			}
+			return true;
+		}
+		return false;
+	}
+
+	private boolean dashIgnoringElementEquals(Elements e1, Elements e2, int i) {
 		int l1 = e1.getLength(i);
 		int l2 = e2.getLength(i);
-		boolean indexed1 = e1.getType(i).isIndexed();
-		boolean indexed2 = e2.getType(i).isIndexed();
 		int i1 = 0;
 		int i2 = 0;
 		while (i1 < l1) {
 			if (i2 >= l2) {
 				return false;
 			}
-			char ch1 = indexed1 ? e1.charAt(i, i1) : Character.toLowerCase(e1.charAt(i, i1));
-			char ch2 = indexed2 ? e2.charAt(i, i2) : Character.toLowerCase(e2.charAt(i, i2));
-			if (!indexed1 && !ElementsParser.isAlphaNumeric(ch1)) {
+			char ch1 = e1.charAt(i, i1);
+			char ch2 = e2.charAt(i, i2);
+			if (ch1 == '-') {
 				i1++;
 			}
-			else if (!indexed2 && !ElementsParser.isAlphaNumeric(ch2)) {
+			else if (ch2 == '-') {
 				i2++;
 			}
 			else if (ch1 != ch2) {
@@ -350,12 +368,12 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 			}
 		}
 		if (i2 < l2) {
-			if (indexed2) {
+			if (e2.getType(i).isIndexed()) {
 				return false;
 			}
 			do {
-				char ch2 = Character.toLowerCase(e2.charAt(i, i2++));
-				if (ElementsParser.isAlphaNumeric(ch2)) {
+				char ch2 = e2.charAt(i, i2++);
+				if (ch2 != '-') {
 					return false;
 				}
 			}
@@ -364,21 +382,23 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 		return true;
 	}
 
-	private boolean dashIgnoringElementEquals(Elements e1, Elements e2, int i) {
+	private boolean defaultElementEquals(Elements e1, Elements e2, int i) {
 		int l1 = e1.getLength(i);
 		int l2 = e2.getLength(i);
+		boolean indexed1 = e1.getType(i).isIndexed();
+		boolean indexed2 = e2.getType(i).isIndexed();
 		int i1 = 0;
 		int i2 = 0;
 		while (i1 < l1) {
 			if (i2 >= l2) {
 				return false;
 			}
-			char ch1 = e1.charAt(i, i1);
-			char ch2 = e2.charAt(i, i2);
-			if (ch1 == '-') {
+			char ch1 = indexed1 ? e1.charAt(i, i1) : Character.toLowerCase(e1.charAt(i, i1));
+			char ch2 = indexed2 ? e2.charAt(i, i2) : Character.toLowerCase(e2.charAt(i, i2));
+			if (!indexed1 && !ElementsParser.isAlphaNumeric(ch1)) {
 				i1++;
 			}
-			else if (ch2 == '-') {
+			else if (!indexed2 && !ElementsParser.isAlphaNumeric(ch2)) {
 				i2++;
 			}
 			else if (ch1 != ch2) {
@@ -390,12 +410,12 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 			}
 		}
 		if (i2 < l2) {
-			if (e2.getType(i).isIndexed()) {
+			if (indexed2) {
 				return false;
 			}
 			do {
-				char ch2 = e2.charAt(i, i2++);
-				if (ch2 != '-') {
+				char ch2 = Character.toLowerCase(e2.charAt(i, i2++));
+				if (ElementsParser.isAlphaNumeric(ch2)) {
 					return false;
 				}
 			}
@@ -404,27 +424,28 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 		return true;
 	}
 
-	private boolean fastElementEquals(Elements e1, Elements e2, int i) {
-		int length1 = e1.getLength(i);
-		int length2 = e2.getLength(i);
-		if (length1 == length2) {
-			int i1 = 0;
-			while (length1-- != 0) {
-				char ch1 = e1.charAt(i, i1);
-				char ch2 = e2.charAt(i, i1);
-				if (ch1 != ch2) {
-					return false;
+	@Override
+	public int hashCode() {
+		int hashCode = this.hashCode;
+		Elements elements = this.elements;
+		if (hashCode == 0 && elements.getSize() != 0) {
+			for (int elementIndex = 0; elementIndex < elements.getSize(); elementIndex++) {
+				int elementHashCode = 0;
+				boolean indexed = elements.getType(elementIndex).isIndexed();
+				int length = elements.getLength(elementIndex);
+				for (int i = 0; i < length; i++) {
+					char ch = elements.charAt(elementIndex, i);
+					if (!indexed) {
+						ch = Character.toLowerCase(ch);
+					}
+					if (ElementsParser.isAlphaNumeric(ch)) {
+						elementHashCode = 31 * elementHashCode + ch;
+					}
 				}
-				i1++;
+				hashCode = 31 * hashCode + elementHashCode;
 			}
-			return true;
 		}
-		return false;
-	}
-
-	@Override
-	public int hashCode() {
-		return 0;
+		return hashCode;
 	}
 
 	@Override

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameTests.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -545,17 +545,18 @@ class ConfigurationPropertyNameTests {
 		ConfigurationPropertyName n13 = ConfigurationPropertyName.of("f-o-o[b-a-r--]");
 		ConfigurationPropertyName n14 = ConfigurationPropertyName.of("[1]");
 		ConfigurationPropertyName n15 = ConfigurationPropertyName.of("[-1]");
-		assertThat(n01.hashCode()).isEqualTo(n02.hashCode());
-		assertThat(n01.hashCode()).isEqualTo(n02.hashCode());
-		assertThat(n01.hashCode()).isEqualTo(n03.hashCode());
-		assertThat(n01.hashCode()).isEqualTo(n04.hashCode());
-		assertThat(n01.hashCode()).isEqualTo(n11.hashCode());
 		assertThat((Object) n01).isEqualTo(n01);
+		assertThat(n01.hashCode()).isEqualTo(n01.hashCode());
 		assertThat((Object) n01).isEqualTo(n02);
+		assertThat(n01.hashCode()).isEqualTo(n02.hashCode());
 		assertThat((Object) n01).isEqualTo(n03);
+		assertThat(n01.hashCode()).isEqualTo(n03.hashCode());
 		assertThat((Object) n01).isEqualTo(n04);
+		assertThat(n01.hashCode()).isEqualTo(n04.hashCode());
 		assertThat((Object) n11).isEqualTo(n03);
+		assertThat(n11.hashCode()).isEqualTo(n03.hashCode());
 		assertThat((Object) n03).isEqualTo(n11);
+		assertThat(n03.hashCode()).isEqualTo(n11.hashCode());
 		assertThat((Object) n01).isNotEqualTo(n05);
 		assertThat((Object) n01).isNotEqualTo(n06);
 		assertThat((Object) n07).isNotEqualTo(n08);