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/**
* Copyright (C) 2011-2012 Typesafe Inc.
*/
package com.crashnote.core.config.helper;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* An immutable map from config paths to config values.
*
*
* Contrast with {@link ConfigObject} which is a map from config keys,
* rather than paths, to config values. A {@code Config} contains a tree of
* {@code ConfigObject}, and {@link Config#root()} returns the tree's root
* object.
*
*
* Throughout the API, there is a distinction between "keys" and "paths". A key
* is a key in a JSON object; it's just a string that's the key in a map. A
* "path" is a parseable expression with a syntax and it refers to a series of
* keys. Path expressions are described in the spec for
* Human-Optimized Config Object Notation. In brief, a path is
* period-separated so "a.b.c" looks for key c in object b in object a in the
* root object. Sometimes double quotes are needed around special characters in
* path expressions.
*
*
* The API for a {@code Config} is in terms of path expressions, while the API
* for a {@code ConfigObject} is in terms of keys. Conceptually, {@code Config}
* is a one-level map from paths to values, while a
* {@code ConfigObject} is a tree of nested maps from keys to values.
*
*
* Use {@link ConfigUtil#joinPath} and {@link ConfigUtil#splitPath} to convert
* between path expressions and individual path elements (keys).
*
*
* Another difference between {@code Config} and {@code ConfigObject} is that
* conceptually, {@code ConfigValue}s with a {@link ConfigValue#valueType()
* valueType()} of {@link ConfigValueType#NULL NULL} exist in a
* {@code ConfigObject}, while a {@code Config} treats null values as if they
* were missing.
*
*
* {@code Config} is an immutable object and thus safe to use from multiple
* threads. There's never a need for "defensive copies."
*
*
* The "getters" on a {@code Config} all work in the same way. They never return
* null, nor do they return a {@code ConfigValue} with
* {@link ConfigValue#valueType() valueType()} of {@link ConfigValueType#NULL
* NULL}. Instead, they throw {@link ConfigException.Missing} if the value is
* completely absent or set to null. If the value is set to null, a subtype of
* {@code ConfigException.Missing} called {@link ConfigException.Null} will be
* thrown. {@link ConfigException.WrongType} will be thrown anytime you ask for
* a type and the value has an incompatible type. Reasonable type conversions
* are performed for you though.
*
*
* If you want to iterate over the contents of a {@code Config}, you can get its
* {@code ConfigObject} with {@link #root()}, and then iterate over the
* {@code ConfigObject} (which implements java.util.Map). Or, you
* can use {@link #entrySet()} which recurses the object tree for you and builds
* up a Set of all path-value pairs where the value is not null.
*
*
* Do not implement {@code Config}; it should only be implemented by
* the config library. Arbitrary implementations will not work because the
* library internals assume a specific concrete implementation. Also, this
* interface is likely to grow new methods over time, so third-party
* implementations will break.
*/
public interface Config extends ConfigMergeable {
/**
* Gets the {@code Config} as a tree of {@link ConfigObject}. This is a
* constant-time operation (it is not proportional to the number of values
* in the {@code Config}).
*
* @return the root object in the configuration
*/
ConfigObject root();
/**
* Gets the origin of the {@code Config}, which may be a file, or a file
* with a line number, or just a descriptive phrase.
*
* @return the origin of the {@code Config} for use in error messages
*/
ConfigOrigin origin();
@Override
Config withFallback(ConfigMergeable other);
/**
* Returns a replacement config with all substitutions (the
* ${foo.bar} syntax, see the
* spec) resolved. Substitutions are looked up using this
* Config as the root object, that is, a substitution
* ${foo.bar} will be replaced with the result of
* getValue("foo.bar").
*
*
* This method uses {@link ConfigResolveOptions#defaults()}, there is
* another variant {@link Config#resolve(ConfigResolveOptions)} which lets
* you specify non-default options.
*
*
* A given {@link Config} must be resolved before using it to retrieve
* config values, but ideally should be resolved one time for your entire
* stack of fallbacks (see {@link Config#withFallback}). Otherwise, some
* substitutions that could have resolved with all fallbacks available may
* not resolve, which will be a user-visible oddity.
*
*
* resolve() should be invoked on root config objects, rather
* than on a subtree (a subtree is the result of something like
* config.getConfig("foo")). The problem with
* resolve() on a subtree is that substitutions are relative to
* the root of the config and the subtree will have no way to get values
* from the root. For example, if you did
* config.getConfig("foo").resolve() on the below config file,
* it would not work:
*
*
* common-value = 10
* foo {
* whatever = ${common-value}
* }
*
*
* @return an immutable object with substitutions resolved
* @throws ConfigException.UnresolvedSubstitution
* if any substitutions refer to nonexistent paths
* @throws ConfigException
* some other config exception if there are other problems
*/
Config resolve();
/**
* Like {@link Config#resolve()} but allows you to specify non-default
* options.
*
* @param options
* resolve options
* @return the resolved Config
*/
Config resolve(ConfigResolveOptions options);
/**
* Validates this config against a reference config, throwing an exception
* if it is invalid. The purpose of this method is to "fail early" with a
* comprehensive list of problems; in general, anything this method can find
* would be detected later when trying to use the config, but it's often
* more user-friendly to fail right away when loading the config.
*
*
* Using this method is always optional, since you can "fail late" instead.
*
*
* You must restrict validation to paths you "own" (those whose meaning are
* defined by your code module). If you validate globally, you may trigger
* errors about paths that happen to be in the config but have nothing to do
* with your module. It's best to allow the modules owning those paths to
* validate them. Also, if every module validates only its own stuff, there
* isn't as much redundant work being done.
*
*
* If no paths are specified in checkValid()'s parameter list,
* validation is for the entire config.
*
*
* If you specify paths that are not in the reference config, those paths
* are ignored. (There's nothing to validate.)
*
*
* Here's what validation involves:
*
*
* - All paths found in the reference config must be present in this
* config or an exception will be thrown.
*
-
* Some changes in type from the reference config to this config will cause
* an exception to be thrown. Not all potential type problems are detected,
* in particular it's assumed that strings are compatible with everything
* except objects and lists. This is because string types are often "really"
* some other type (system properties always start out as strings, or a
* string like "5ms" could be used with {@link #getMilliseconds}). Also,
* it's allowed to set any type to null or override null with any type.
*
-
* Any unresolved substitutions in this config will cause a validation
* failure; both the reference config and this config should be resolved
* before validation. If the reference config is unresolved, it's a bug in
* the caller of this method.
*
*
*
* If you want to allow a certain setting to have a flexible type (or
* otherwise want validation to be looser for some settings), you could
* either remove the problematic setting from the reference config provided
* to this method, or you could intercept the validation exception and
* screen out certain problems. Of course, this will only work if all other
* callers of this method are careful to restrict validation to their own
* paths, as they should be.
*
*
* If validation fails, the thrown exception contains a list of all problems
* found. See {@link ConfigException.ValidationFailed#problems}. The
* exception's getMessage() will have all the problems
* concatenated into one huge string, as well.
*
*
* Again, checkValid() can't guess every domain-specific way a
* setting can be invalid, so some problems may arise later when attempting
* to use the config. checkValid() is limited to reporting
* generic, but common, problems such as missing settings and blatant type
* incompatibilities.
*
* @param reference
* a reference configuration
* @param restrictToPaths
* only validate values underneath these paths that your code
* module owns and understands
* @throws ConfigException.ValidationFailed
* if there are any validation issues
* @throws ConfigException.NotResolved
* if this config is not resolved
* @throws ConfigException.BugOrBroken
* if the reference config is unresolved or caller otherwise
* misuses the API
*/
void checkValid(Config reference, String... restrictToPaths);
/**
* Checks whether a value is present and non-null at the given path. This
* differs in two ways from {@code Map.containsKey()} as implemented by
* {@link ConfigObject}: it looks for a path expression, not a key; and it
* returns false for null values, while {@code containsKey()} returns true
* indicating that the object contains a null value for the key.
*
*
* If a path exists according to {@link #hasPath(String)}, then
* {@link #getValue(String)} will never throw an exception. However, the
* typed getters, such as {@link #getInt(String)}, will still throw if the
* value is not convertible to the requested type.
*
* @param path
* the path expression
* @return true if a non-null value is present at the path
* @throws ConfigException.BadPath
* if the path expression is invalid
*/
boolean hasPath(String path);
/**
* Returns true if the {@code Config}'s root object contains no key-value
* pairs.
*
* @return true if the configuration is empty
*/
boolean isEmpty();
/**
* Returns the set of path-value pairs, excluding any null values, found by
* recursing {@link #root() the root object}. Note that this is very
* different from root().entrySet() which returns the set of
* immediate-child keys in the root object and includes null values.
*
* @return set of paths with non-null values, built up by recursing the
* entire tree of {@link ConfigObject}
*/
Set> entrySet();
/**
*
* @param path
* path expression
* @return the boolean value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to boolean
*/
boolean getBoolean(String path);
/**
* @param path
* path expression
* @return the numeric value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to a number
*/
Number getNumber(String path);
/**
* @param path
* path expression
* @return the 32-bit integer value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to an int (for example it is out
* of range, or it's a boolean value)
*/
int getInt(String path);
/**
* @param path
* path expression
* @return the 64-bit long value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to a long
*/
long getLong(String path);
/**
* @param path
* path expression
* @return the floating-point value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to a double
*/
double getDouble(String path);
/**
* @param path
* path expression
* @return the string value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to a string
*/
String getString(String path);
/**
* @param path
* path expression
* @return the {@link ConfigObject} value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to an object
*/
ConfigObject getObject(String path);
/**
* @param path
* path expression
* @return the nested {@code Config} value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to a Config
*/
Config getConfig(String path);
/**
* Gets the value at the path as an unwrapped Java boxed value (
* {@link java.lang.Boolean Boolean}, {@link java.lang.Integer Integer}, and
* so on - see {@link ConfigValue#unwrapped()}).
*
* @param path
* path expression
* @return the unwrapped value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
*/
Object getAnyRef(String path);
/**
* Gets the value at the given path, unless the value is a
* null value or missing, in which case it throws just like
* the other getters. Use {@code get()} on the {@link
* Config#root()} object (or other object in the tree) if you
* want an unprocessed value.
*
* @param path
* path expression
* @return the value at the requested path
* @throws ConfigException.Missing
* if value is absent or null
*/
ConfigValue getValue(String path);
/**
* Gets a value as a size in bytes (parses special strings like "128M"). If
* the value is already a number, then it's left alone; if it's a string,
* it's parsed understanding unit suffixes such as "128K", as documented in
* the the
* spec.
*
* @param path
* path expression
* @return the value at the requested path, in bytes
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to Long or String
* @throws ConfigException.BadValue
* if value cannot be parsed as a size in bytes
*/
Long getBytes(String path);
/**
* Get value as a duration in milliseconds. If the value is already a
* number, then it's left alone; if it's a string, it's parsed understanding
* units suffixes like "10m" or "5ns" as documented in the the
* spec.
*
* @param path
* path expression
* @return the duration value at the requested path, in milliseconds
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to Long or String
* @throws ConfigException.BadValue
* if value cannot be parsed as a number of milliseconds
*/
Long getMilliseconds(String path);
/**
* Get value as a duration in nanoseconds. If the value is already a number
* it's taken as milliseconds and converted to nanoseconds. If it's a
* string, it's parsed understanding unit suffixes, as for
* {@link #getMilliseconds(String)}.
*
* @param path
* path expression
* @return the duration value at the requested path, in nanoseconds
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to Long or String
* @throws ConfigException.BadValue
* if value cannot be parsed as a number of nanoseconds
*/
Long getNanoseconds(String path);
/**
* Gets a list value (with any element type) as a {@link ConfigList}, which
* implements {@code java.util.List}. Throws if the path is
* unset or null.
*
* @param path
* the path to the list value.
* @return the {@link ConfigList} at the path
* @throws ConfigException.Missing
* if value is absent or null
* @throws ConfigException.WrongType
* if value is not convertible to a ConfigList
*/
ConfigList getList(String path);
List getBooleanList(String path);
List getNumberList(String path);
List getIntList(String path);
List getLongList(String path);
List getDoubleList(String path);
List getStringList(String path);
List getObjectList(String path);
List getConfigList(String path);
List getAnyRefList(String path);
List getBytesList(String path);
List getMillisecondsList(String path);
List getNanosecondsList(String path);
/**
* Clone the config with only the given path (and its children) retained;
* all sibling paths are removed.
*
* @param path
* path to keep
* @return a copy of the config minus all paths except the one specified
*/
Config withOnlyPath(String path);
/**
* Clone the config with the given path removed.
*
* @param path
* path to remove
* @return a copy of the config minus the specified path
*/
Config withoutPath(String path);
}