110 lines
3.8 KiB
C#
110 lines
3.8 KiB
C#
using DevDisciples.Parsing;
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namespace DevDisciples.Json.Tools;
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public static partial class JsonPath
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{
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public static partial class Parser
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{
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public static List<IJsonPathSyntax> Parse(string path)
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{
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var pathTokens = Lexer.Default.Lex("<path>", path);
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var context = new Context(pathTokens.ToArray());
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context.Match(JsonPathToken.DollarSign); // Match the '$' eagerly. This will make it optional by default.
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var syntax = new List<IJsonPathSyntax>();
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while (!context.Ended())
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syntax.Add(Expression(context));
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return syntax;
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}
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private static IJsonPathSyntax Expression(Context context)
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{
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if (context.Match(JsonPathToken.Dot))
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return PropertyAccessorExpression(context);
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if (context.Match(JsonPathToken.LeftBracket))
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return IndexAccessorExpression(context);
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throw context.Error("Invalid expression.");
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}
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private static IJsonPathSyntax PropertyAccessorExpression(Context context)
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{
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var token = context.Previous();
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IJsonPathSyntax getter;
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if (context.Match(JsonPathToken.Asterisk))
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getter = new WildCardSyntax(context.Previous());
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else if (context.Match(JsonPathToken.Identifier))
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getter = new PropertySyntax(context.Previous());
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else throw context.Error("Expected a getter expression");
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return new PropertyAccessorSyntax(token, getter);
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}
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private static IJsonPathSyntax IndexAccessorExpression(Context context)
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{
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var token = context.Previous();
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IJsonPathSyntax syntax;
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if (context.Match(JsonPathToken.Asterisk))
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syntax = new WildCardSyntax(context.Previous());
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else if (context.Match(JsonPathToken.Number))
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syntax = ArrayIndexExpression(token, context);
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else if (context.Match(JsonPathToken.String))
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syntax = ObjectIndexExpression(token, context);
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else throw context.Error("Expected an index expression.");
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context.Consume(JsonPathToken.RightBracket, "Expected ']' after index expression.");
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return syntax;
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}
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private static IJsonPathSyntax ArrayIndexExpression(Lexer<JsonPathToken>.Token token, Context context)
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{
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var index = context.Previous();
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if (!context.Match(JsonPathToken.Comma)) return new ArrayIndexSyntax(token, index);
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var indexes = new List<Lexer<JsonPathToken>.Token> { index };
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do
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{
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index = context.Consume(JsonPathToken.Number, "Invalid array index.");
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if (!int.TryParse(index.Lexeme, out _)) throw context.Error(index, "Invalid array index.");
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indexes.Add(index);
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} while (!context.Ended() && context.Match(JsonPathToken.Comma));
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return new ArrayIndexListSyntax(token, indexes.ToArray());
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}
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private static IJsonPathSyntax ObjectIndexExpression(Lexer<JsonPathToken>.Token token, Context context)
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{
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var index = context.Previous();
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if (!context.Match(JsonPathToken.Comma)) return new ObjectIndexSyntax(token, index);
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var indexes = new List<Lexer<JsonPathToken>.Token> { index };
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do
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{
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index = context.Consume(JsonPathToken.String, "Invalid object index.");
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indexes.Add(index);
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} while (!context.Ended() && context.Match(JsonPathToken.Comma));
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return new ObjectIndexListSyntax(token, indexes.ToArray());
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}
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}
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} |