[Parse] Factor out 'isEffectsSpecifier()'

Author: rintaro

include/swift/Parse/Parser.h

@@ -1357,6 +1357,9 @@ class Parser {
                                       SourceLoc &asyncLoc, SourceLoc &throwsLoc,
                                       bool *rethrows);
 
+  /// Returns 'true' if \p T is considered effects specifier.
+  bool isEffectsSpecifier(const Token &T);
+
   //===--------------------------------------------------------------------===//
   // Pattern Parsing
 

lib/Parse/ParseExpr.cpp

@@ -2341,23 +2341,10 @@ ParserStatus Parser::parseClosureSignatureIfPresent(
   inLoc = SourceLoc();
 
   // Consume 'async', 'throws', and 'rethrows', but in any order.
-  auto consumeAsyncThrows = [&] {
-    while (true) {
-      if (shouldParseExperimentalConcurrency() &&
-          Tok.isContextualKeyword("async")) {
-        consumeToken();
-        continue;
-      }
-      if (consumeIf(tok::kw_throws) || consumeIf(tok::kw_rethrows))
-        continue;
-
-      if (Tok.is(tok::code_complete) && !Tok.isAtStartOfLine()) {
-        consumeToken();
-        continue;
-      }
-
-      break;
-    }
+  auto consumeEffectsSpecifiers = [&] {
+    while (isEffectsSpecifier(Tok) ||
+           (Tok.is(tok::code_complete) && !Tok.isAtStartOfLine()))
+      consumeToken();
   };
 
   // If we have a leading token that may be part of the closure signature, do a
@@ -2381,7 +2368,7 @@ ParserStatus Parser::parseClosureSignatureIfPresent(
 
       // Consume the ')', if it's there.
       if (consumeIf(tok::r_paren)) {
-        consumeAsyncThrows();
+        consumeEffectsSpecifiers();
 
         // Parse the func-signature-result, if present.
         if (consumeIf(tok::arrow)) {
@@ -2403,7 +2390,7 @@ ParserStatus Parser::parseClosureSignatureIfPresent(
         return makeParserSuccess();
       }
 
-      consumeAsyncThrows();
+      consumeEffectsSpecifiers();
 
       // Parse the func-signature-result, if present.
       if (consumeIf(tok::arrow)) {

lib/Parse/ParsePattern.cpp

@@ -821,6 +821,21 @@ Parser::parseFunctionSignature(Identifier SimpleName,
   return Status;
 }
 
+bool Parser::isEffectsSpecifier(const Token &T) {
+  // NOTE: If this returns 'true', that token must be handled in
+  //       'parseEffectsSpecifiers()'.
+
+  if (shouldParseExperimentalConcurrency() &&
+      T.isContextualKeyword("async"))
+    return true;
+
+  if (T.isAny(tok::kw_throws, tok::kw_rethrows) ||
+      (T.isAny(tok::kw_throw, tok::kw_try) && !T.isAtStartOfLine()))
+    return true;
+
+  return false;
+}
+
 ParserStatus Parser::parseEffectsSpecifiers(SourceLoc existingArrowLoc,
                                             SourceLoc &asyncLoc,
                                             SourceLoc &throwsLoc,

lib/Parse/ParseType.cpp

@@ -1639,17 +1639,6 @@ bool Parser::isAtFunctionTypeArrow() {
   if (Tok.is(tok::arrow))
     return true;
 
-  auto isEffectsSpecifier = [this](const Token &T) -> bool {
-    if (shouldParseExperimentalConcurrency() &&
-        T.isContextualKeyword("async"))
-      return true;
-    if (T.isAny(tok::kw_throws, tok::kw_rethrows))
-      return true;
-    if (T.isAny(tok::kw_throw, tok::kw_try) && !T.isAtStartOfLine())
-      return true;
-    return false;
-  };
-
   if (isEffectsSpecifier(Tok)) {
     if (peekToken().is(tok::arrow))
       return true;