Optimisation: Reduce parsing of JSON object

.gitignore

@@ -3,5 +3,6 @@
 /.swiftpm
 /Packages
 /*.xcodeproj
+/docs
 xcuserdata/
 Package.resolved

Sources/JMESPath/Ast.swift

@@ -1,31 +1,44 @@
-//
-//  File.swift
-//
-//
-//  Created by Adam Fowler on 27/05/2021.
-//
-
+/// JMES expression abstract syntax tree
 public indirect enum Ast: Equatable {
+    /// compares two nodes using a comparator
     case comparison(comparator: Comparator, lhs: Ast, rhs: Ast)
+    /// if `predicate` evaluates to a truthy value returns result from `then`
     case condition(predicate: Ast, then: Ast)
+    /// returns the current node
     case identity
+    /// used by functions to dynamically evaluate argument values
     case expRef(ast: Ast)
+    /// evaluates nodes and then flattens it one level
     case flatten(node: Ast)
+    /// function name and a vector of function argument expressions
     case function(name: String, args: [Ast])
+    /// extracts a key value from an object
     case field(name: String)
+    /// extracts an indexed value from an array
     case index(index: Int)
+    /// resolves to a literal value
     case literal(value: JMESVariable)
+    /// resolves to a list of evaluated expressions
     case multiList(elements: [Ast])
+    /// resolves to a map of key/evaluated expression pairs
     case multiHash(elements: [String: Ast])
+    /// evaluates to true/false based on expression
     case not(node: Ast)
+    /// evalutes `lhs` and pushes each value through to `rhs`
     case projection(lhs: Ast, rhs: Ast)
+    /// evaluates expression and if result is an object then return array of its values
     case objectValues(node: Ast)
+    /// evaluates `lhs` and if not truthy returns, otherwise evaluates `rhs`
     case and(lhs: Ast, rhs: Ast)
+    /// evaluates `lhs` and if truthy returns, otherwise evaluates `rhs`
     case or(lhs: Ast, rhs: Ast)
+    /// returns a slice of an array
     case slice(start: Int?, stop: Int?, step: Int)
+    /// evalutes `lhs` and then provides that value to `rhs`
     case subExpr(lhs: Ast, rhs: Ast)
 }
 
+/// Comparator used in comparison AST nodes
 public enum Comparator: Equatable {
     case equal
     case notEqual
@@ -34,6 +47,7 @@ public enum Comparator: Equatable {
     case greaterThan
     case greaterThanOrEqual
 
+    /// initialise `Comparator` from `Token`
     init(from token: Token) throws {
         switch token {
         case .equals: self = .equal

Sources/JMESPath/Error.swift

@@ -3,9 +3,9 @@
 /// Provides two errors, compile time and run time errors
 public struct JMESPathError: Error, Equatable {
     /// Error that occurred while compiling JMESPath
-    public static func compileTime(_ message: String) -> Self { .init(value: .compileTime(message))}
+    public static func compileTime(_ message: String) -> Self { .init(value: .compileTime(message)) }
     /// Error that occurred while running a search
-    public static func runtime(_ message: String) -> Self { .init(value: .runtime(message))}
+    public static func runtime(_ message: String) -> Self { .init(value: .runtime(message)) }
 
     private enum Internal: Equatable {
         case compileTime(String)

Sources/JMESPath/Expression.swift

@@ -23,7 +23,7 @@ public struct Expression {
     /// - Throws: JMESPathError
     /// - Returns: Search result
     public func search<Value>(json: String, as: Value.Type = Value.self, runtime: JMESRuntime = .init()) throws -> Value? {
-        return try search(json: json, runtime: runtime) as? Value
+        return try self.search(json: json, runtime: runtime) as? Value
     }
 
     /// Search Swift type
@@ -35,7 +35,7 @@ public struct Expression {
     /// - Throws: JMESPathError
     /// - Returns: Search result
     public func search<Value>(_ any: Any, as: Value.Type = Value.self, runtime: JMESRuntime = .init()) throws -> Value? {
-        return try search(any, runtime: runtime) as? Value
+        return try self.search(any, runtime: runtime) as? Value
     }
 
     /// Search JSON