mirror of
https://github.com/mbierlee/mirage-config.git
synced 2024-11-15 04:44:01 +01:00
607 lines
17 KiB
D
607 lines
17 KiB
D
/**
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* Base utilities for working with configurations.
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*
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* Authors:
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* Mike Bierlee, m.bierlee@lostmoment.com
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* Copyright: 2022 Mike Bierlee
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* License:
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* This software is licensed under the terms of the MIT license.
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* The full terms of the license can be found in the LICENSE file.
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*/
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module mirage.config;
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import std.exception : enforce;
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import std.string : split, startsWith, endsWith, join, lastIndexOf, strip;
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import std.conv : to, ConvException;
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import std.file : readText;
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/**
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* Used by the ConfigDictionary when something goes wrong when reading configuration.
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*/
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class ConfigReadException : Exception {
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this(string msg, string file = __FILE__, size_t line = __LINE__) {
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super(msg, file, line);
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}
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}
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/**
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* Used by ConfigFactory instances when loading or parsing configuration fails.
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*/
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class ConfigCreationException : Exception {
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this(string msg, string file = __FILE__, size_t line = __LINE__) {
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super(msg, file, line);
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}
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}
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/**
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* Used by ConfigDictionary when there is something wrong with the path when calling ConfigDictionary.get()
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*/
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class PathParseException : Exception {
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this(string msg, string path, string file = __FILE__, size_t line = __LINE__) {
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string fullMsg = msg ~ " (Path: " ~ path ~ ")";
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super(fullMsg, file, line);
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}
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}
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/**
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* The configuration tree is made up of specific types of ConfigNodes.
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* Used as generic type for ConfigFactory and ConfigDictionary.
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*/
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interface ConfigNode {
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string nodeType();
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}
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/**
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* A configuration item that is any sort of primitive value (strings, numbers or null).
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*/
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class ValueNode : ConfigNode {
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string value;
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this() {
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}
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this(string value) {
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this.value = value;
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}
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string nodeType() {
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return "value";
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}
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}
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/**
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* A configuration item that is an object.
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*
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* ObjectNodes contain a node dictionary that points to other ConfigNodes.
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*/
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class ObjectNode : ConfigNode {
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ConfigNode[string] children;
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this() {
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}
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this(ConfigNode[string] children) {
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this.children = children;
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}
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this(string[string] values) {
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foreach (key, value; values) {
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children[key] = new ValueNode(value);
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}
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}
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string nodeType() {
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return "object";
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}
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}
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/**
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* A configuration item that is an array.
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*
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* Contains other ConfigNodes as children.
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*/
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class ArrayNode : ConfigNode {
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ConfigNode[] children;
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this() {
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}
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this(ConfigNode[] children...) {
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this.children = children;
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}
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this(string[] values...) {
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foreach (string value; values) {
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children ~= new ValueNode(value);
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}
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}
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string nodeType() {
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return "array";
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}
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}
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private interface PathSegment {
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}
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private class ArrayPathSegment : PathSegment {
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const size_t index;
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this(const size_t index) {
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this.index = index;
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}
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}
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private class PropertyPathSegment : PathSegment {
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const string propertyName;
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this(const string propertyName) {
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this.propertyName = propertyName;
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}
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}
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private class ConfigPath {
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private const string path;
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private string[] previousSegments;
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private string[] segments;
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this(const string path) {
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this.path = path;
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segmentAndNormalize(path);
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}
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private void segmentAndNormalize(string path) {
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foreach (segment; path.split(".")) {
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auto trimmedSegment = segment.strip;
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if (trimmedSegment.length <= 0) {
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continue;
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}
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if (trimmedSegment.endsWith("]") && !trimmedSegment.startsWith("[")) {
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auto openBracketPos = trimmedSegment.lastIndexOf("[");
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if (openBracketPos != -1) {
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segments ~= trimmedSegment[0 .. openBracketPos];
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segments ~= trimmedSegment[openBracketPos .. $];
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continue;
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}
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}
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segments ~= trimmedSegment;
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}
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}
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PathSegment getNextSegment() {
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if (segments.length == 0) {
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return null;
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}
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PathSegment ret(PathSegment segment) {
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previousSegments ~= segments[0];
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segments = segments[1 .. $];
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return segment;
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}
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string segment = segments[0];
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if (segment.startsWith("[") && segment.endsWith("]")) {
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if (segment.length <= 2) {
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throw new PathParseException("Path has array accessor but no index specified", path);
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}
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auto indexString = segment[1 .. $ - 1];
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try {
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auto index = indexString.to!size_t;
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return ret(new ArrayPathSegment(index));
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} catch (ConvException e) {
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throw new PathParseException("Value '" ~ indexString ~ "' is not acceptable as an array index", path);
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}
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}
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return ret(new PropertyPathSegment(segment));
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}
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string getCurrentPath() {
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return previousSegments.join(".");
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}
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}
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/**
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* A ConfigDictionary contains the configuration tree and facilities to get values from that tree.
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*/
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class ConfigDictionary {
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ConfigNode rootNode;
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this() {
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}
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this(ConfigNode rootNode) {
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this.rootNode = rootNode;
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}
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/**
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* Get values from the configuration using config path notation.
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*
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* Params:
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* configPath = Path to the wanted config value. The path is separated by dots, e.g. "server.public.hostname".
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* Values from arrays can be selected by brackets, for example: "server[3].hostname.ports[0]".
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* When the config is just a value, for example just a string, it can be fetched by just specifying "." as path.
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* Although the path should be universally the same over all types of config files, some might not lend to this structure,
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* and have a more specific way of retrieving data from the config. See the examples and specific config factories for
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* more details.
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*
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* Returns: The value at the path in the configuration. To convert it use get!T().
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*/
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string get(string configPath) {
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auto path = new ConfigPath(configPath);
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auto node = getNodeAt(path);
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auto value = cast(ValueNode) node;
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if (value) {
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return value.value;
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} else {
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throw new ConfigReadException(
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"Value expected but " ~ node.nodeType ~ " found at path: " ~ createExceptionPath(
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path));
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}
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}
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/**
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* Get values from the configuration and attempts to convert them to the specified type.
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*
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* Params:
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* configPath = Path to the wanted config value. See get().
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* Returns: The value at the path in the configuration.
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*/
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ConvertToType get(ConvertToType)(string configPath) {
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return get(configPath).to!ConvertToType;
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}
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/**
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* Fetch a sub-section of the config as another config.
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*
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* Commonly used for example to fetch further configuration from arrays, e.g.: `getConfig("http.servers[3]")`
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* which then returns the rest of the config at that path.
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*
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* Params:
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* configPath = Path to the wanted config. See get().
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* Returns: A sub-section of the configuration.
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*/
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ConfigDictionary getConfig(string configPath) {
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auto path = new ConfigPath(configPath);
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auto node = getNodeAt(path);
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return new ConfigDictionary(node);
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}
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string createExceptionPath(ConfigPath path) {
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return "'" ~ path.path ~ "' (at '" ~ path.getCurrentPath() ~ "')";
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}
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private ConfigNode getNodeAt(ConfigPath path) {
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enforce!ConfigReadException(rootNode !is null, "The config is empty");
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auto currentNode = rootNode;
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PathSegment currentPathSegment = path.getNextSegment();
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void throwPathNotExists() {
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throw new ConfigReadException("Path does not exist: " ~ createExceptionPath(path));
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}
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void ifNotNullPointer(void* obj, void delegate() fn) {
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if (obj) {
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fn();
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} else {
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throwPathNotExists();
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}
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}
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void ifNotNull(Object obj, void delegate() fn) {
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if (obj) {
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fn();
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} else {
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throwPathNotExists();
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}
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}
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while (currentPathSegment !is null) {
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if (currentNode is null) {
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throwPathNotExists();
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}
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auto valueNode = cast(ValueNode) currentNode;
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if (valueNode) {
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throwPathNotExists();
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}
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auto arrayPath = cast(ArrayPathSegment) currentPathSegment;
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if (arrayPath) {
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auto arrayNode = cast(ArrayNode) currentNode;
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ifNotNull(arrayNode, {
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if (arrayNode.children.length < arrayPath.index) {
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throw new ConfigReadException(
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"Array index out of bounds: " ~ createExceptionPath(path));
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}
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currentNode = arrayNode.children[arrayPath.index];
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});
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}
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auto propertyPath = cast(PropertyPathSegment) currentPathSegment;
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if (propertyPath) {
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auto objectNode = cast(ObjectNode) currentNode;
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ifNotNull(objectNode, {
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auto propertyNode = propertyPath.propertyName in objectNode.children;
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ifNotNullPointer(propertyNode, {
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currentNode = *propertyNode;
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});
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});
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}
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currentPathSegment = path.getNextSegment();
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}
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return currentNode;
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}
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}
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/**
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* The base class used by configuration factories for specific file types.
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*/
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abstract class ConfigFactory {
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/**
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* Loads a configuration from the specified path from disk.
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*
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* Params:
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* path = Path to file. OS dependent, but UNIX paths are generally working.
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* Returns: The parsed configuration.
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*/
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ConfigDictionary loadFile(string path) {
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auto json = readText(path);
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return parseConfig(json);
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}
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/**
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* Parse configuration from the given string.
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*
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* Params:
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* contents = Text contents of the config to be parsed.
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* Returns: The parsed configuration.
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*/
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ConfigDictionary parseConfig(string contents);
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}
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version (unittest) {
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import std.exception : assertThrown;
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import std.math.operations : isClose;
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@("Dictionary creation")
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unittest {
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auto root = new ObjectNode([
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"english": new ArrayNode([new ValueNode("one"), new ValueNode("two")]),
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"spanish": new ArrayNode(new ValueNode("uno"), new ValueNode("dos"))
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]);
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auto config = new ConfigDictionary();
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config.rootNode = root;
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}
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@("Get value in config with empty root fails")
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unittest {
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auto config = new ConfigDictionary();
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assertThrown!ConfigReadException(config.get("."));
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}
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@("Get value in root with empty path")
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unittest {
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auto config = new ConfigDictionary(new ValueNode("hehehe"));
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assert(config.get("") == "hehehe");
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}
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@("Get value in root with just a dot")
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unittest {
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auto config = new ConfigDictionary(new ValueNode("yup"));
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assert(config.get(".") == "yup");
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}
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@("Get value in root fails when root is not a value")
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unittest {
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auto config = new ConfigDictionary(new ArrayNode());
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assertThrown!ConfigReadException(config.get("."));
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}
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@("Get array value from root")
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unittest {
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auto config = new ConfigDictionary(new ArrayNode("aap", "noot", "mies"));
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assert(config.get("[0]") == "aap");
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assert(config.get("[1]") == "noot");
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assert(config.get("[2]") == "mies");
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}
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@("Get value from object at root")
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unittest {
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auto config = new ConfigDictionary(new ObjectNode([
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"aap": "monkey",
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"noot": "nut",
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"mies": "mies" // It's a name!
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])
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);
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assert(config.get("aap") == "monkey");
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assert(config.get("noot") == "nut");
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assert(config.get("mies") == "mies");
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}
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@("Get value from object in object")
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unittest {
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auto config = new ConfigDictionary(
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new ObjectNode([
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"server": new ObjectNode([
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"port": "8080"
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])
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])
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);
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assert(config.get("server.port") == "8080");
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}
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@("Get value from array in object")
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unittest {
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auto config = new ConfigDictionary(
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new ObjectNode([
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"hostname": new ArrayNode(["google.com", "dlang.org"])
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])
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);
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assert(config.get("hostname.[1]") == "dlang.org");
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}
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@("Exception is thrown when array out of bounds when fetching from root")
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unittest {
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auto config = new ConfigDictionary(
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new ArrayNode([
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"google.com", "dlang.org"
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])
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);
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assertThrown!ConfigReadException(config.get("[5]"));
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}
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@("Exception is thrown when array out of bounds when fetching from object")
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unittest {
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auto config = new ConfigDictionary(
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new ObjectNode([
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"hostname": new ArrayNode(["google.com", "dlang.org"])
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])
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);
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assertThrown!ConfigReadException(config.get("hostname.[5]"));
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}
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@("Exception is thrown when path does not exist")
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unittest {
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auto config = new ConfigDictionary(new ObjectNode(
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[
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"hostname": new ObjectNode(["cluster": new ValueNode("")])
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])
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);
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assertThrown!ConfigReadException(config.get("hostname.cluster.spacey"));
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}
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@("Exception is thrown when given path terminates too early")
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unittest {
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auto config = new ConfigDictionary(new ObjectNode(
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[
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"hostname": new ObjectNode(["cluster": new ValueNode(null)])
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])
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);
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assertThrown!ConfigReadException(config.get("hostname"));
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}
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@("Exception is thrown when given path does not exist because config is an array")
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unittest {
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auto config = new ConfigDictionary(new ArrayNode());
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assertThrown!ConfigReadException(config.get("hostname"));
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}
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@("Get value from objects in array")
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unittest {
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auto config = new ConfigDictionary(new ArrayNode(
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new ObjectNode(["wrong": "yes"]),
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new ObjectNode(["wrong": "no"]),
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new ObjectNode(["wrong": "very"]),
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));
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assert(config.get("[1].wrong") == "no");
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}
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@("Get value from config with mixed types")
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unittest {
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auto config = new ConfigDictionary(
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new ObjectNode([
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"uno": cast(ConfigNode) new ValueNode("one"),
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"dos": cast(ConfigNode) new ArrayNode(["nope", "two"]),
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"tres": cast(ConfigNode) new ObjectNode(["thisone": "three"])
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])
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);
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assert(config.get("uno") == "one");
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assert(config.get("dos.[1]") == "two");
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assert(config.get("tres.thisone") == "three");
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}
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@("Ignore empty segments")
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unittest {
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auto config = new ConfigDictionary(
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new ObjectNode(
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[
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"one": new ObjectNode(["two": new ObjectNode(["three": "four"])])
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])
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);
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assert(config.get(".one..two...three....") == "four");
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}
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@("Support conventional array indexing notation")
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unittest {
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auto config = new ConfigDictionary(
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new ObjectNode(
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[
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"one": new ObjectNode([
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"two": new ArrayNode(["dino", "mino"])
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])
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])
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);
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assert(config.get("one.two[1]") == "mino");
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}
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@("Get and convert values")
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unittest {
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auto config = new ConfigDictionary(
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new ObjectNode([
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"uno": new ValueNode("1223"),
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"dos": new ValueNode("true"),
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"tres": new ValueNode("Hi you"),
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"quatro": new ValueNode("1.3")
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])
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);
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assert(config.get!int("uno") == 1223);
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assert(config.get!bool("dos") == true);
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assert(config.get!string("tres") == "Hi you");
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assert(isClose(config.get!float("quatro"), 1.3));
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}
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@("Get config from array")
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unittest {
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auto configOne = new ConfigDictionary(new ObjectNode(
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[
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"servers": new ArrayNode([
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new ObjectNode(["hostname": "lala.com"]),
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new ObjectNode(["hostname": "lele.com"])
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])
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])
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);
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auto config = configOne.getConfig("servers[0]");
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assert(config.get("hostname") == "lala.com");
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}
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@("Trim spaces in path segments")
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unittest {
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auto config = new ConfigDictionary(
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new ObjectNode(["que": new ObjectNode(["pasa hombre": "not much"])])
|
|
);
|
|
|
|
assert(config.get(" que. pasa hombre ") == "not much");
|
|
}
|
|
}
|