Fix package tangle and polish prefix support

Polish the prefix support introduced in commit a8592f3 and fix a
package tangle between `boot.context.properties.source` and `boot.env`.

The `Prefix` interface has now been moved into a new default method on
`OriginLookup`.

See gh-3450

Author: philwebb

spring-boot-project/spring-boot-docs/src/docs/asciidoc/spring-boot-features.adoc

@@ -993,6 +993,7 @@ The `YamlPropertiesFactoryBean` loads YAML as `Properties` and the `YamlMapFacto
 You can also use the `YamlPropertySourceLoader` class if you want to load YAML as a Spring `PropertySource`.
 
 
+
 [[boot-features-external-config-random-values]]
 === Configuring Random Values
 The `RandomValuePropertySource` is useful for injecting random values (for example, into secrets or test cases).
@@ -1013,13 +1014,15 @@ The `+random.int*+` syntax is `OPEN value (,max) CLOSE` where the `OPEN,CLOSE` a
 If `max` is provided, then `value` is the minimum value and `max` is the maximum value (exclusive).
 
 
+
 [[boot-features-external-config-system-environment]]
 === Configuring System Environment Properties
 Spring Boot supports setting a prefix for environment properties.
 This is useful if the system environment is shared by multiple Spring Boot applications with different configuration requirements.
 The prefix for system environment properties can be set directly on `SpringApplication`.
 
-For example, if you set the prefix to `input`, a property such as `foo.bar` will also be resolved as `input.foo.bar` in the system environment.
+For example, if you set the prefix to `input`, a property such as `remote.timeout` will also be resolved as `input.remote.timeout` in the system environment.
+
 
 
 [[boot-features-external-config-typesafe-configuration-properties]]

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplication.java

@@ -364,9 +364,8 @@ private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners
 		listeners.environmentPrepared(bootstrapContext, environment);
 		DefaultPropertiesPropertySource.moveToEnd(environment);
 		configureAdditionalProfiles(environment);
-		if (environment.getProperty("spring.main.environment-prefix") != null) {
-			throw new IllegalStateException("Environment prefix cannot be set via properties.");
-		}
+		Assert.state(!environment.containsProperty("spring.main.environment-prefix"),
+				"Environment prefix cannot be set via properties.");
 		bindToSpringApplication(environment);
 		if (!this.isCustomEnvironment) {
 			environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,
@@ -1181,10 +1180,22 @@ public void setResourceLoader(ResourceLoader resourceLoader) {
 		this.resourceLoader = resourceLoader;
 	}
 
+	/**
+	 * Return a prefix that should be applied when obtaining configuration properties from
+	 * the system environment.
+	 * @return the environment property prefix
+	 * @since 2.5.0
+	 */
 	public String getEnvironmentPrefix() {
 		return this.environmentPrefix;
 	}
 
+	/**
+	 * Set the prefix that should be applied when obtaining configuration properties from
+	 * the system environment.
+	 * @param environmentPrefix the environment property prefix to set
+	 * @since 2.5.0
+	 */
 	public void setEnvironmentPrefix(String environmentPrefix) {
 		this.environmentPrefix = environmentPrefix;
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -24,6 +24,7 @@
 import java.util.function.Function;
 
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * A configuration property name composed of elements separated by dots. User created
@@ -195,19 +196,32 @@ public int getNumberOfElements() {
 	}
 
 	/**
-	 * Create a new {@link ConfigurationPropertyName} by appending the given elements.
-	 * @param elements the elements to append
+	 * Create a new {@link ConfigurationPropertyName} by appending the given suffix.
+	 * @param suffix the elements to append
 	 * @return a new {@link ConfigurationPropertyName}
 	 * @throws InvalidConfigurationPropertyNameException if the result is not valid
 	 */
-	public ConfigurationPropertyName append(String elements) {
-		if (elements == null) {
+	public ConfigurationPropertyName append(String suffix) {
+		if (!StringUtils.hasLength(suffix)) {
 			return this;
 		}
-		Elements additionalElements = probablySingleElementOf(elements);
+		Elements additionalElements = probablySingleElementOf(suffix);
 		return new ConfigurationPropertyName(this.elements.append(additionalElements));
 	}
 
+	/**
+	 * Create a new {@link ConfigurationPropertyName} by appending the given suffix.
+	 * @param suffix the elements to append
+	 * @return a new {@link ConfigurationPropertyName}
+	 * @since 2.5.0
+	 */
+	public ConfigurationPropertyName append(ConfigurationPropertyName suffix) {
+		if (suffix == null) {
+			return this;
+		}
+		return new ConfigurationPropertyName(this.elements.append(suffix.elements));
+	}
+
 	/**
 	 * Return the parent of this {@link ConfigurationPropertyName} or
 	 * {@link ConfigurationPropertyName#EMPTY} if there is no parent.
@@ -232,6 +246,27 @@ public ConfigurationPropertyName chop(int size) {
 		return new ConfigurationPropertyName(this.elements.chop(size));
 	}
 
+	/**
+	 * Return a new {@link ConfigurationPropertyName} by based on this name offset by
+	 * specific element index. For example, {@code chop(1)} on the name {@code foo.bar}
+	 * will return {@code bar}.
+	 * @param offset the element offset
+	 * @return the sub name
+	 * @since 2.5.0
+	 */
+	public ConfigurationPropertyName subName(int offset) {
+		if (offset == 0) {
+			return this;
+		}
+		if (offset == getNumberOfElements()) {
+			return EMPTY;
+		}
+		if (offset < 0 || offset > getNumberOfElements()) {
+			throw new IndexOutOfBoundsException("Offset: " + offset + ", NumberOfElements: " + getNumberOfElements());
+		}
+		return new ConfigurationPropertyName(this.elements.subElements(offset));
+	}
+
 	/**
 	 * Returns {@code true} if this element is an immediate parent of the specified name.
 	 * @param name the name to check
@@ -718,19 +753,31 @@ Elements append(Elements additional) {
 			ElementType[] type = new ElementType[size];
 			System.arraycopy(this.type, 0, type, 0, this.size);
 			System.arraycopy(additional.type, 0, type, this.size, additional.size);
-			CharSequence[] resolved = newResolved(size);
+			CharSequence[] resolved = newResolved(0, size);
 			for (int i = 0; i < additional.size; i++) {
 				resolved[this.size + i] = additional.get(i);
 			}
 			return new Elements(this.source, size, this.start, this.end, type, resolved);
 		}
 
 		Elements chop(int size) {
-			CharSequence[] resolved = newResolved(size);
+			CharSequence[] resolved = newResolved(0, size);
 			return new Elements(this.source, size, this.start, this.end, this.type, resolved);
 		}
 
-		private CharSequence[] newResolved(int size) {
+		Elements subElements(int offset) {
+			int size = this.size - offset;
+			CharSequence[] resolved = newResolved(offset, size);
+			int[] start = new int[size];
+			System.arraycopy(this.start, offset, start, 0, size);
+			int[] end = new int[size];
+			System.arraycopy(this.end, offset, end, 0, size);
+			ElementType[] type = new ElementType[size];
+			System.arraycopy(this.type, offset, type, 0, size);
+			return new Elements(this.source, size, start, end, type, resolved);
+		}
+
+		private CharSequence[] newResolved(int offset, int size) {
 			CharSequence[] resolved = new CharSequence[size];
 			if (this.resolved != null) {
 				System.arraycopy(this.resolved, 0, resolved, 0, Math.min(size, this.size));

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -20,6 +20,7 @@
 
 import org.springframework.boot.origin.OriginTrackedValue;
 import org.springframework.core.env.PropertySource;
+import org.springframework.util.StringUtils;
 
 /**
  * A source of {@link ConfigurationProperty ConfigurationProperties}.
@@ -78,9 +79,10 @@ default ConfigurationPropertySource withAliases(ConfigurationPropertyNameAliases
 	 * Return a variant of this source that supports a prefix.
 	 * @param prefix the prefix for properties in the source
 	 * @return a {@link ConfigurationPropertySource} instance supporting a prefix
+	 * @since 2.5.0
 	 */
 	default ConfigurationPropertySource withPrefix(String prefix) {
-		return new PrefixedConfigurationPropertySource(this, prefix);
+		return (StringUtils.hasText(prefix)) ? new PrefixedConfigurationPropertySource(this, prefix) : this;
 	}
 
 	/**

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -21,6 +21,7 @@
 import java.util.stream.Stream;
 
 import org.springframework.boot.origin.OriginTrackedValue;
+import org.springframework.util.StringUtils;
 
 /**
  * A {@link ConfigurationPropertySource} with a fully {@link Iterable} set of entries.
@@ -75,7 +76,7 @@ default IterableConfigurationPropertySource withAliases(ConfigurationPropertyNam
 
 	@Override
 	default IterableConfigurationPropertySource withPrefix(String prefix) {
-		return new PrefixedIterableConfigurationPropertySource(this, prefix);
+		return (StringUtils.hasText(prefix)) ? new PrefixedIterableConfigurationPropertySource(this, prefix) : this;
 	}
 
 }

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

@@ -17,7 +17,6 @@
 package org.springframework.boot.context.properties.source;
 
 import org.springframework.util.Assert;
-import org.springframework.util.StringUtils;
 
 /**
  * A {@link ConfigurationPropertySource} supporting a prefix.
@@ -28,13 +27,17 @@ class PrefixedConfigurationPropertySource implements ConfigurationPropertySource
 
 	private final ConfigurationPropertySource source;
 
-	private final String prefix;
+	private final ConfigurationPropertyName prefix;
 
 	PrefixedConfigurationPropertySource(ConfigurationPropertySource source, String prefix) {
 		Assert.notNull(source, "Source must not be null");
-		Assert.notNull(prefix, "Prefix must not be null");
+		Assert.hasText(prefix, "Prefix must not be empty");
 		this.source = source;
-		this.prefix = prefix;
+		this.prefix = ConfigurationPropertyName.of(prefix);
+	}
+
+	protected final ConfigurationPropertyName getPrefix() {
+		return this.prefix;
 	}
 
 	@Override
@@ -47,11 +50,7 @@ public ConfigurationProperty getConfigurationProperty(ConfigurationPropertyName
 	}
 
 	private ConfigurationPropertyName getPrefixedName(ConfigurationPropertyName name) {
-		if (!StringUtils.hasText(this.prefix)) {
-			return name;
-		}
-		String prefix = this.prefix + ".";
-		return ConfigurationPropertyName.of(prefix + name);
+		return this.prefix.append(name);
 	}
 
 	@Override
@@ -68,8 +67,4 @@ protected ConfigurationPropertySource getSource() {
 		return this.source;
 	}
 
-	protected String getPrefix() {
-		return this.prefix;
-	}
-
 }

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

@@ -18,8 +18,6 @@
 
 import java.util.stream.Stream;
 
-import org.springframework.util.StringUtils;
-
 /**
  * An iterable {@link PrefixedConfigurationPropertySource}.
  *
@@ -34,17 +32,11 @@ class PrefixedIterableConfigurationPropertySource extends PrefixedConfigurationP
 
 	@Override
 	public Stream<ConfigurationPropertyName> stream() {
-		if (!StringUtils.hasText(getPrefix())) {
-			return getSource().stream();
-		}
-		ConfigurationPropertyName prefix = ConfigurationPropertyName.of(getPrefix());
-		return getSource().stream().map((propertyName) -> {
-			if (prefix.isAncestorOf(propertyName)) {
-				String name = propertyName.toString();
-				return ConfigurationPropertyName.of(name.substring(getPrefix().length() + 1));
-			}
-			return propertyName;
-		});
+		return getSource().stream().map(this::stripPrefix);
+	}
+
+	private ConfigurationPropertyName stripPrefix(ConfigurationPropertyName name) {
+		return (getPrefix().isAncestorOf(name)) ? name.subName(getPrefix().getNumberOfElements()) : name;
 	}
 
 	@Override

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -24,7 +24,7 @@
 import java.util.Random;
 import java.util.function.Function;
 
-import org.springframework.boot.env.Prefixed;
+import org.springframework.boot.origin.OriginLookup;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.MutablePropertySources;
 import org.springframework.core.env.PropertySource;
@@ -64,8 +64,8 @@ private ConfigurationPropertySource adapt(PropertySource<?> source) {
 			return result;
 		}
 		result = SpringConfigurationPropertySource.from(source);
-		if (source instanceof Prefixed) {
-			result = result.withPrefix(((Prefixed) source).getPrefix());
+		if (source instanceof OriginLookup) {
+			result = result.withPrefix(((OriginLookup<?>) source).getPrefix());
 		}
 		this.cache.put(source, result);
 		return result;