[LLDB] Add boolean literals to DIL.

This adds the ability to recognize (and create ValueObjects for)
boolean literals ("true", "false") to DIL. This is a preliminary
step to adding type casting (and also for the ternary op).

Author: cmtice

lldb/docs/dil-expr-lang.ebnf

@@ -16,6 +16,7 @@ postfix_expression = primary_expression
                    | postfix_expression "->" id_expression ;
 
 primary_expression = numeric_literal
+                   | boolean_literal
                    | id_expression
                    | "(" expression ")" ;
 
@@ -35,6 +36,8 @@ integer_literal = ? Integer constant: hexademical, decimal, octal, binary ? ;
 numeric_literal = ? Integer constant: hexademical, decimal, octal, binary ?
                 | ? Floating constant ? ;
 
+boolean_literal = "true" | "false" ;
+
 register = "$" ? Register name ? ;
 
 nested_name_specifier = type_name "::"

lldb/include/lldb/ValueObject/DILAST.h

@@ -20,6 +20,7 @@ namespace lldb_private::dil {
 enum class NodeKind {
   eArraySubscriptNode,
   eBitExtractionNode,
+  eBooleanLiteralNode,
   eErrorNode,
   eFloatLiteralNode,
   eIdentifierNode,
@@ -226,6 +227,23 @@ class FloatLiteralNode : public ASTNode {
   llvm::APFloat m_value;
 };
 
+class BooleanLiteralNode : public ASTNode {
+public:
+  BooleanLiteralNode(uint32_t location, bool value)
+      : ASTNode(location, NodeKind::eBooleanLiteralNode), m_value(value) {}
+
+  llvm::Expected<lldb::ValueObjectSP> Accept(Visitor *v) const override;
+
+  bool GetValue() const & { return m_value; }
+
+  static bool classof(const ASTNode *node) {
+    return node->GetKind() == NodeKind::eBooleanLiteralNode;
+  }
+
+private:
+  bool m_value;
+};
+
 /// This class contains one Visit method for each specialized type of
 /// DIL AST node. The Visit methods are used to dispatch a DIL AST node to
 /// the correct function in the DIL expression evaluator for evaluating that
@@ -247,6 +265,8 @@ class Visitor {
   Visit(const IntegerLiteralNode *node) = 0;
   virtual llvm::Expected<lldb::ValueObjectSP>
   Visit(const FloatLiteralNode *node) = 0;
+  virtual llvm::Expected<lldb::ValueObjectSP>
+  Visit(const BooleanLiteralNode *node) = 0;
 };
 
 } // namespace lldb_private::dil

lldb/include/lldb/ValueObject/DILEval.h

@@ -58,6 +58,8 @@ class Interpreter : Visitor {
   Visit(const IntegerLiteralNode *node) override;
   llvm::Expected<lldb::ValueObjectSP>
   Visit(const FloatLiteralNode *node) override;
+  llvm::Expected<lldb::ValueObjectSP>
+  Visit(const BooleanLiteralNode *node) override;
 
   llvm::Expected<CompilerType>
   PickIntegerType(lldb::TypeSystemSP type_system,

lldb/include/lldb/ValueObject/DILLexer.h

@@ -31,6 +31,8 @@ class Token {
     float_constant,
     identifier,
     integer_constant,
+    kw_false,
+    kw_true,
     l_paren,
     l_square,
     minus,

lldb/include/lldb/ValueObject/DILParser.h

@@ -99,11 +99,14 @@ class DILParser {
   ASTNodeUP ParseNumericLiteral();
   ASTNodeUP ParseIntegerLiteral();
   ASTNodeUP ParseFloatingPointLiteral();
+  ASTNodeUP ParseBooleanLiteral();
 
   void BailOut(const std::string &error, uint32_t loc, uint16_t err_len);
 
   void Expect(Token::Kind kind);
 
+  void ExpectOneOf(std::vector<Token::Kind> kinds_vec);
+
   void TentativeParsingRollback(uint32_t saved_idx) {
     if (m_error)
       llvm::consumeError(std::move(m_error));

lldb/source/ValueObject/DILAST.cpp

@@ -46,4 +46,9 @@ llvm::Expected<lldb::ValueObjectSP> FloatLiteralNode::Accept(Visitor *v) const {
   return v->Visit(this);
 }
 
+llvm::Expected<lldb::ValueObjectSP>
+BooleanLiteralNode::Accept(Visitor *v) const {
+  return v->Visit(this);
+}
+
 } // namespace lldb_private::dil

lldb/source/ValueObject/DILEval.cpp

@@ -602,4 +602,10 @@ Interpreter::Visit(const FloatLiteralNode *node) {
                                                   "result");
 }
 
+llvm::Expected<lldb::ValueObjectSP>
+Interpreter::Visit(const BooleanLiteralNode *node) {
+  bool value = node->GetValue();
+  return ValueObject::CreateValueObjectFromBool(m_target, value, "result");
+}
+
 } // namespace lldb_private::dil

lldb/source/ValueObject/DILLexer.cpp

@@ -34,6 +34,10 @@ llvm::StringRef Token::GetTokenName(Kind kind) {
     return "identifier";
   case Kind::integer_constant:
     return "integer_constant";
+  case Kind::kw_false:
+    return "false";
+  case Kind::kw_true:
+    return "true";
   case Kind::l_paren:
     return "l_paren";
   case Kind::l_square:
@@ -42,7 +46,6 @@ llvm::StringRef Token::GetTokenName(Kind kind) {
     return "minus";
   case Kind::period:
     return "period";
-    return "l_square";
   case Kind::plus:
     return "plus";
   case Kind::r_paren:
@@ -137,8 +140,14 @@ llvm::Expected<Token> DILLexer::Lex(llvm::StringRef expr,
     return Token(kind, maybe_number->str(), position);
   }
   std::optional<llvm::StringRef> maybe_word = IsWord(expr, remainder);
-  if (maybe_word)
-    return Token(Token::identifier, maybe_word->str(), position);
+  if (maybe_word) {
+    llvm::StringRef word = *maybe_word;
+    Token::Kind kind = llvm::StringSwitch<Token::Kind>(word)
+                           .Case("false", Token::kw_false)
+                           .Case("true", Token::kw_true)
+                           .Default(Token::identifier);
+    return Token(kind, word.str(), position);
+  }
 
   constexpr std::pair<Token::Kind, const char *> operators[] = {
       {Token::amp, "&"},      {Token::arrow, "->"},   {Token::coloncolon, "::"},

lldb/source/ValueObject/DILParser.cpp

@@ -180,12 +180,15 @@ ASTNodeUP DILParser::ParsePostfixExpression() {
 //
 //  primary_expression:
 //    numeric_literal
+//    boolean_literal
 //    id_expression
 //    "(" expression ")"
 //
 ASTNodeUP DILParser::ParsePrimaryExpression() {
   if (CurToken().IsOneOf({Token::integer_constant, Token::float_constant}))
     return ParseNumericLiteral();
+  if (CurToken().IsOneOf({Token::kw_true, Token::kw_false}))
+    return ParseBooleanLiteral();
   if (CurToken().IsOneOf(
           {Token::coloncolon, Token::identifier, Token::l_paren})) {
     // Save the source location for the diagnostics message.
@@ -336,6 +339,20 @@ std::string DILParser::ParseUnqualifiedId() {
   return identifier;
 }
 
+// Parse an boolean_literal.
+//
+//  boolean_literal:
+//    "true"
+//    "false"
+//
+ASTNodeUP DILParser::ParseBooleanLiteral() {
+  ExpectOneOf(std::vector<Token::Kind>{Token::kw_true, Token::kw_false});
+  uint32_t loc = CurToken().GetLocation();
+  bool literal_value = CurToken().Is(Token::kw_true);
+  m_dil_lexer.Advance();
+  return std::make_unique<BooleanLiteralNode>(loc, literal_value);
+}
+
 void DILParser::BailOut(const std::string &error, uint32_t loc,
                         uint16_t err_len) {
   if (m_error)
@@ -444,4 +461,12 @@ void DILParser::Expect(Token::Kind kind) {
   }
 }
 
+void DILParser::ExpectOneOf(std::vector<Token::Kind> kinds_vec) {
+  if (!CurToken().IsOneOf(kinds_vec)) {
+    BailOut(llvm::formatv("expected any of ({0}), got: {1}",
+                          llvm::iterator_range(kinds_vec), CurToken()),
+            CurToken().GetLocation(), CurToken().GetSpelling().length());
+  }
+}
+
 } // namespace lldb_private::dil