[ASTGen] Start using 'TokenSyntax.rawText'

`TokenSyntax.text` causes intiation of heap allocated `Swift.String` for
each access. `TokenSyntax.rawText` is faster than that because it's just
a reference to the pre-allocated buffer. Also, converting to
`BridgedString` is simplar, and guaranteed to be free, unlike bridging
via `String.withUTF8(_:)`

Author: rintaro

lib/ASTGen/Sources/ASTGen/Bridge.swift

@@ -12,7 +12,7 @@
 
 import ASTBridging
 import BasicBridging
-import SwiftSyntax
+@_spi(RawSyntax) import SwiftSyntax
 
 protocol BridgedNullable: ExpressibleByNilLiteral {
   associatedtype RawPtr
@@ -100,6 +100,12 @@ extension String {
   }
 }
 
+extension SyntaxText {
+  var bridged: BridgedStringRef {
+    BridgedStringRef(data: self.baseAddress, count: self.count)
+  }
+}
+
 /// Allocate a copy of the given string as a null-terminated UTF-8 string.
 func allocateBridgedString(
   _ string: String

lib/ASTGen/Sources/ASTGen/Literals.swift

@@ -18,13 +18,16 @@ extension ASTGenVisitor {
     let openDelimiterOrQuoteLoc = (node.openingPounds ?? node.openingQuote).bridgedSourceLoc(in: self)
 
     // FIXME: Handle interpolated strings.
+    // FIXME: Avoid 'String' instantiation
     var segment = node.segments.first!.as(StringSegmentSyntax.self)!.content.text
     return segment.withBridgedString { bridgedSegment in
       return .createParsed(self.ctx, value: bridgedSegment, loc: openDelimiterOrQuoteLoc)
     }
   }
 
   public func generate(integerLiteralExpr node: IntegerLiteralExprSyntax) -> BridgedIntegerLiteralExpr {
+    // FIXME: Avoid 'String' instantiation
+    // FIXME: Strip '_'.
     var segment = node.literal.text
     return segment.withBridgedString { bridgedSegment in
       return .createParsed(ctx, value: bridgedSegment, loc: node.literal.bridgedSourceLoc(in: self))

lib/ASTGen/Sources/ASTGen/Types.swift

@@ -13,7 +13,7 @@
 import ASTBridging
 import BasicBridging
 import SwiftDiagnostics
-@_spi(ExperimentalLanguageFeatures) import SwiftSyntax
+@_spi(ExperimentalLanguageFeatures) @_spi(RawSyntax) import SwiftSyntax
 
 extension EffectSpecifiersSyntax {
   var thrownError: TypeSyntax? {
@@ -203,14 +203,14 @@ extension ASTGenVisitor {
   public func generate(metatypeType node: MetatypeTypeSyntax) -> BridgedTypeRepr {
     let baseType = generate(type: node.baseType)
     let tyLoc = node.metatypeSpecifier.bridgedSourceLoc(in: self)
-    if node.metatypeSpecifier.text == "Type" {
+    if node.metatypeSpecifier.rawText == "Type" {
       return BridgedMetatypeTypeRepr.createParsed(
         self.ctx,
         base: baseType,
         typeKeywordLoc: tyLoc
       )
     } else {
-      assert(node.metatypeSpecifier.text == "Protocol")
+      assert(node.metatypeSpecifier.rawText == "Protocol")
       return BridgedProtocolTypeRepr.createParsed(
         self.ctx,
         base: baseType,
@@ -298,7 +298,7 @@ extension ASTGenVisitor {
   public func generate(someOrAnyType node: SomeOrAnyTypeSyntax) -> BridgedTypeRepr {
     let someOrAnyLoc = node.someOrAnySpecifier.bridgedSourceLoc(in: self)
     let baseTy = generate(type: node.constraint)
-    if node.someOrAnySpecifier.text == "some" {
+    if node.someOrAnySpecifier.rawText == "some" {
       return BridgedOpaqueReturnTypeRepr.createParsed(
         self.ctx,
         someKeywordLoc: someOrAnyLoc,
@@ -368,10 +368,7 @@ extension ASTGenVisitor {
         }
 
         let nameSyntax = identType.name
-        var name = nameSyntax.text
-        let typeAttrKind = name.withBridgedString { bridgedName in
-          BridgedTypeAttrKind(from: bridgedName)
-        }
+        let typeAttrKind = BridgedTypeAttrKind(from: nameSyntax.rawText.bridged)
         let atLoc = attribute.atSign.bridgedSourceLoc(in: self)
         let attrLoc = nameSyntax.bridgedSourceLoc(in: self)
         switch typeAttrKind {