Refactor generation of SwiftSyntaxBuilder

.gitignore

@@ -9,4 +9,5 @@
 # dependency versions.
 Package.resolved
 
-.DS_Store
+.DS_Store
+*.pyc

Sources/SwiftSyntaxBuilder/BuildableBaseProtocols.swift.gyb

@@ -0,0 +1,85 @@
+%{
+  from gyb_syntax_support.kinds import SYNTAX_BASE_KINDS
+  from gyb_helpers import SyntaxBuildableType, conformance_clause
+  # -*- mode: Swift -*-
+  # Ignore the following admonition it applies to the resulting .swift file only
+}%
+//// Automatically Generated From BuildableBaseProtocols.swift.gyb.
+//// Do Not Edit Directly!
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftSyntax
+
+%{
+# `SyntaxCollectionBuildable` and `ExpressibleAsSyntaxCollectionBuildable` don't exist because of the following reason:
+# Through `ExpressibleAs*` conformances, a syntax kind might conform to `ExpressibleAsSyntaxCollectionBuildable` via different paths, thus the implementation of `createSyntaxCollectionBuildable` is ambiguous.
+# We have the same issue for `ExpressibleAsSyntaxBuildable`, but in that case the solution is simple: Create a custom implementaiton of `createSyntaxBuildable` that doesn't perform any of the conversions via the `ExpressibleAs` protocols.
+# For `SyntaxCollection` we would need to perform at least one conversion to end up with a type that we can put inside a `SyntaxCollection`, so there is no single canonical implementation.
+# Since the types don't provide any value, we don't generate them for now.
+}%
+% for kind in [syntax_base_kind for syntax_base_kind in SYNTAX_BASE_KINDS if syntax_base_kind != 'SyntaxCollection']:
+%   type = SyntaxBuildableType(kind)
+%   buildable_conformances = [type.expressible_as(), type.list_buildable()] # Types that the `*Buildable` conforms to
+%   list_conformances = [] # Types that the `*ListBuildable` conforms to
+%   if kind != 'Syntax':
+%     syntax_type = SyntaxBuildableType('Syntax')
+%     list_conformances.append(syntax_type.list_buildable())
+%     buildable_conformances.append(syntax_type.buildable())
+%   end
+
+public protocol ${type.list_buildable()}${conformance_clause(list_conformances)} {
+  /// Builds list of `${type.syntax()}`s.
+  /// - Parameter format: The `Format` to use.
+  /// - Parameter leadingTrivia: Replaces the the last leading trivia if not nil.
+  /// - Returns: A list of `${type.syntax()}`.
+  func build${type.base_name()}List(format: Format, leadingTrivia: Trivia?) -> [${type.syntax()}]
+}
+
+public protocol ${type.buildable()}${conformance_clause(buildable_conformances)} {
+  /// Builds a `${type.syntax()}`.
+  /// - Parameter format: The `Format` to use.
+  /// - Parameter leadingTrivia: Replaces the the last leading trivia if not nil.
+  /// - Returns: A list of `${type.syntax()}`.
+  func build${type.base_name()}(format: Format, leadingTrivia: Trivia?) -> ${type.syntax()}
+}
+
+public extension ${type.buildable()} {
+  /// Satisfies conformance to `${type.expressible_as()}`.
+  func create${type.buildable_base_name()}() -> ${type.buildable()} {
+    return self
+  }
+
+  /// Builds list of `${type.syntax()}`s.
+  /// - Parameter format: The `Format` to use.
+  /// - Parameter leadingTrivia: Replaces the the last leading trivia if not nil.
+  /// - Returns: A list of `${type.syntax()}`.
+  ///
+  /// Satisfies conformance to `${type.list_buildable()}`.
+  func build${type.base_name()}List(format: Format, leadingTrivia: Trivia? = nil) -> [${type.syntax()}] {
+    return [build${type.base_name()}(format: format, leadingTrivia: leadingTrivia)]
+  }
+
+% if kind != 'Syntax':
+  /// Builds a `${type.syntax()}`.
+  /// - Parameter format: The `Format` to use.
+  /// - Parameter leadingTrivia: Replaces the the last leading trivia if not nil.
+  /// - Returns: A new `Syntax` with the builded `${type.syntax()}`.
+  ///
+  /// Satisfies conformance to `SyntaxBuildable`.
+  func buildSyntax(format: Format, leadingTrivia: Trivia? = nil) -> Syntax {
+    return Syntax(build${type.base_name()}(format: format, leadingTrivia: leadingTrivia))
+  }
+% end
+}
+
+% end

Sources/SwiftSyntaxBuilder/BuildableCollectionNodes.swift.gyb

@@ -0,0 +1,84 @@
+%{
+  from gyb_syntax_support import SYNTAX_NODES
+  from gyb_helpers import flat_documentation, SyntaxBuildableChild, SyntaxBuildableNode
+  # -*- mode: Swift -*-
+  # Ignore the following admonition it applies to the resulting .swift file only
+}%
+//// Automatically Generated From BuildableCollectionNodes.swift.gyb.
+//// Do Not Edit Directly!
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftSyntax
+
+% for node in [SyntaxBuildableNode(syntax_node) for syntax_node in SYNTAX_NODES if syntax_node.is_syntax_collection()]:
+%   type = node.type()
+%   element_type = node.collection_element_type()
+%   if node.documentation():
+/// ${node.documentation()}
+%   end
+public struct ${type.buildable()}: ExpressibleByArrayLiteral, SyntaxBuildable, ${type.expressible_as()} {
+  let elements: [${element_type.buildable()}]
+
+  /// Creates a `${type.buildable()}` with the provided list of elements.
+  /// - Parameters:
+  ///   - elements: A list of `${element_type.expressible_as()}`
+  public init(_ elements: [${element_type.expressible_as()}]) {
+%   if element_type.is_token():
+    self.elements = elements
+%   else:
+    self.elements = elements.map { $0.create${element_type.buildable_base_name()}() }
+%   end
+  }
+
+  public init(arrayLiteral elements: ${element_type.expressible_as()}...) {
+    self.init(elements)
+  }
+
+  public func build${type.base_name()}(format: Format, leadingTrivia: Trivia? = nil) -> ${type.syntax()} {
+%   if element_type.is_token():
+    let result = SyntaxFactory.make${type.base_name()}(elements)
+%   else:
+%     if node.elements_separated_by_newline():
+%       element_leading_trivia = 'Trivia.newlines(1) + format._makeIndent()'
+%     else:
+%       element_leading_trivia = 'nil'
+%     end
+    let result = SyntaxFactory.make${type.base_name()}(elements.map {
+      $0.build${element_type.base_name()}(format: format, leadingTrivia: ${element_leading_trivia})
+    })
+%   end
+    if let leadingTrivia = leadingTrivia {
+      return result.withLeadingTrivia(leadingTrivia + (result.leadingTrivia ?? []))
+    } else {
+      return result
+    }
+  }
+
+  public func buildSyntax(format: Format, leadingTrivia: Trivia? = nil) -> Syntax {
+    return Syntax(build${type.base_name()}(format: format, leadingTrivia: leadingTrivia))
+  }
+
+  /// Conformance to `${type.expressible_as()}`.
+  public func create${type.buildable_base_name()}() -> ${type.buildable()} {
+    return self
+  }
+
+  /// `${type.buildable()}` might conform to `SyntaxBuildable` via different `ExpressibleAs*` paths.
+  /// Thus, there are multiple default implementations for `createSyntaxBuildable`, some of which perform conversions through `ExpressibleAs*` protocols.
+  /// To resolve the ambiguity, provide a fixed implementation that doesn't perform any conversions.
+  public func createSyntaxBuildable() -> SyntaxBuildable {
+    return self
+  }
+}
+
+% end

Sources/SwiftSyntaxBuilder/BuildableNodes.swift.gyb

@@ -0,0 +1,134 @@
+%{
+  from gyb_syntax_support import SYNTAX_NODES
+  from gyb_helpers import SyntaxBuildableNode
+  # -*- mode: Swift -*-
+  # Ignore the following admonition it applies to the resulting .swift file only
+}%
+//// Automatically Generated From BuildableNodes.swift.gyb.
+//// Do Not Edit Directly!
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftSyntax
+
+% for node in [SyntaxBuildableNode(syntax_node) for syntax_node in SYNTAX_NODES if syntax_node.is_buildable()]:
+%   type = node.type()
+%   base_type = node.base_type()
+%   if node.documentation():
+/// ${node.documentation()}
+%   end
+public struct ${type.buildable()}: ${base_type.buildable()}, ${type.expressible_as()} {
+%   children = node.children()
+%   for child in children:
+  let ${child.name()}: ${child.type().buildable()}
+%   end
+
+  /// Creates a `${type.buildable()}` using the provided parameters.
+  /// - Parameters:
+%   for child in children:
+  ///   - ${child.name()}: ${child.documentation()}
+%   end
+  public init(
+    ${',\n    '.join(['%s: %s%s' % (
+      child.name(),
+      child.type().expressible_as(),
+      child.type().default_initialization()
+    ) for child in children])}
+  ) {
+%   for child in children:
+%     assert_stmt = child.generate_assert_stmt_text_choices(child.name())
+    self.${child.name()} = ${child.type().generate_expr_convert_param_type_to_storage_type(child.name())}
+%     if assert_stmt:
+    ${assert_stmt}
+%     end
+%   end
+  }
+
+%{
+    create_convenience_initializer = False # Only create the convenience initializer if at least one parameter is different than in the initializer defined above
+    # Keep track of init parameter and result builder parameters in different lists to make sure result builder params occur at the end, so they can use trailing closure syntax
+    convenience_init_normal_parameters = []
+    convenience_init_result_builder_parameters = []
+    delegated_init_args = []
+    for child in node.children():
+      produce_expr = None # The expression that is used to call the default initializer defined above
+      if child.type().is_syntax_collection(): # Allow initializing syntax collections with result builders
+        create_convenience_initializer = True
+        default_value = ' = { nil }' if child.type().is_optional else ' = { %s([]) }' % (child.type().buildable())
+        convenience_init_result_builder_parameters.append('@%s %sBuilder: () -> %s%s' % (child.type().non_optional().result_builder(), child.name(), child.type().expressible_as(), default_value))
+        produce_expr = '%sBuilder()' % child.name()
+      elif child.type().token() and not child.type().token().text: # Allow initializing identifier or a token without default text with String value
+        create_convenience_initializer = True
+        if child.type().is_optional:
+          param_type = 'String?'
+          produce_expr = '%s.map(TokenSyntax.%s)' % (child.name(), child.type().token().swift_kind())
+        else:
+          param_type = 'String'
+          produce_expr = 'TokenSyntax.%s(%s)' % (child.type().token().swift_kind(), child.name())
+        convenience_init_normal_parameters.append('%s: %s' % (child.name(), param_type))
+      else:
+        convenience_init_normal_parameters.append('%s: %s%s' % (child.name(), child.type().expressible_as(), child.type().default_initialization()))
+        produce_expr = child.name()
+      delegated_init_args.append('%s: %s' % (child.name(), produce_expr))
+}%
+%   if create_convenience_initializer:
+  /// A convenience initializer that allows:
+  ///  - Initializing syntax collections using result builders
+  ///  - Initializing tokens without default text using strings
+  public init(
+    ${',\n    '.join(convenience_init_normal_parameters + convenience_init_result_builder_parameters)}
+  ) {
+    self.init(
+      ${',\n      '.join(delegated_init_args)}
+    )
+  }
+%   end
+
+  func build${type.base_name()}(format: Format, leadingTrivia: Trivia? = nil) -> ${type.syntax()} {
+    let result = SyntaxFactory.make${type.base_name()}(
+      ${',\n      '.join(['%s: %s' % (child.name(), child.generate_expr_build_syntax_node(child.name(), 'format')) for child in children])}
+    )
+    if let leadingTrivia = leadingTrivia {
+      return result.withLeadingTrivia(leadingTrivia + (result.leadingTrivia ?? []))
+    } else {
+      return result
+    }
+  }
+
+  /// Conformance to `${base_type.buildable()}`.
+  public func build${base_type.base_name()}(format: Format, leadingTrivia: Trivia? = nil) -> ${base_type.syntax()} {
+    let result = build${type.base_name()}(format: format, leadingTrivia: leadingTrivia)
+    return ${base_type.syntax()}(result)
+  }
+
+  /// Conformance to `${type.expressible_as()}`.
+  public func create${type.buildable_base_name()}() -> ${type.buildable()} {
+    return self
+  }
+
+  /// `${type.buildable()}` might conform to `${base_type.expressible_as()}` via different `ExpressibleAs*` paths.
+  /// Thus, there are multiple default implementations for `create${base_type.buildable_base_name()}`, some of which perform conversions through `ExpressibleAs*` protocols.
+  /// To resolve the ambiguity, provide a fixed implementation that doesn't perform any conversions.
+  public func create${base_type.buildable_base_name()}() -> ${base_type.buildable()} {
+    return self
+  }
+
+% if base_type.base_name() != 'Syntax':
+  /// `${type.buildable()}` might conform to `SyntaxBuildable` via different `ExpressibleAs*` paths.
+  /// Thus, there are multiple default implementations for `createSyntaxBuildable`, some of which perform conversions through `ExpressibleAs*` protocols.
+  /// To resolve the ambiguity, provide a fixed implementation that doesn't perform any conversions.
+  public func createSyntaxBuildable() -> SyntaxBuildable {
+    return self
+  }
+% end
+}
+% end