CppStd:lex.pptoken

C++11

C++14

C++17

C++20

C++23

[edit]

Source: https://timsong-cpp.github.io/cppwp/n3337/lex.pptoken

List of Tables [tab]
List of Figures [fig]
1 General [intro]
2 Lexical conventions [lex]
2.1 Separate translation [lex.separate]
2.2 Phases of translation [lex.phases]
2.3 Character sets [lex.charset]
2.4 Trigraph sequences [lex.trigraph]
2.5 Preprocessing tokens [lex.pptoken]
2.6 Alternative tokens [lex.digraph]
2.7 Tokens [lex.token]
2.8 Comments [lex.comment]
2.9 Header names [lex.header]
2.10 Preprocessing numbers [lex.ppnumber]
2.11 Identifiers [lex.name]
2.12 Keywords [lex.key]
2.13 Operators and punctuators [lex.operators]
2.14 Literals [lex.literal]

2.5 Preprocessing tokens [lex.pptoken]

	Syntax (BNF) preprocessing-token: header-name identifier pp-number character-literal user-defined-character-literal string-literal user-defined-string-literal preprocessing-op-or-punc each non-white-space character that cannot be one of the above
1	Each preprocessing token that is converted to a token ([lex.token]) shall have the lexical form of a keyword, an identifier, a literal, an operator, or a punctuator.
2	A preprocessing token is the minimal lexical element of the language in translation phases 3 through 6. The categories of preprocessing token are: header names, identifiers, preprocessing numbers, character literals (including user-defined character literals), string literals (including user-defined string literals), preprocessing operators and punctuators, and single non-white-space characters that do not lexically match the other preprocessing token categories. If a ' or a " character matches the last category, the behavior is undefined. Preprocessing tokens can be separated by white space; this consists of comments ([lex.comment]), or white-space characters (space, horizontal tab, new-line, vertical tab, and form-feed), or both. As described in Clause [cpp], in certain circumstances during translation phase 4, white space (or the absence thereof) serves as more than preprocessing token separation. White space can appear within a preprocessing token only as part of a header name or between the quotation characters in a character literal or string literal.
3	If the input stream has been parsed into preprocessing tokens up to a given character:
(3.1)	If the next character begins a sequence of characters that could be the prefix and initial double quote of a raw string literal, such as R", the next preprocessing token shall be a raw string literal. Between the initial and final double quote characters of the raw string, any transformations performed in phases 1 and 2 (trigraphs, universal-character-names, and line splicing) are reverted; this reversion shall apply before any d-char, r-char, or delimiting parenthesis is identified. The raw string literal is defined as the shortest sequence of characters that matches the raw-string pattern encoding-prefixopt R raw-string
(3.2)	Otherwise, if the next three characters are <:: and the subsequent character is neither : nor >, the < is treated as a preprocessor token by itself and not as the first character of the alternative token <:.
(3.3)	Otherwise, the next preprocessing token is the longest sequence of characters that could constitute a preprocessing token, even if that would cause further lexical analysis to fail. Example #define R "x" const char* s = R"y"; // ill-formed raw string, not "x" "y"
4	ExampleThe program fragment 1Ex is parsed as a preprocessing number token (one that is not a valid floating or integer literal token), even though a parse as the pair of preprocessing tokens 1 and Ex might produce a valid expression (for example, if Ex were a macro defined as +1). Similarly, the program fragment 1E1 is parsed as a preprocessing number (one that is a valid floating literal token), whether or not E is a macro name.
5	ExampleThe program fragment x+++++y is parsed as x ++ ++ + y, which, if x and y have integral types, violates a constraint on increment operators, even though the parse x ++ + ++ y might yield a correct expression.

[edit]

Source: https://timsong-cpp.github.io/cppwp/n4140/lex.pptoken

List of Tables [tab]
List of Figures [fig]
1 General [intro]
2 Lexical conventions [lex]
2.1 Separate translation [lex.separate]
2.2 Phases of translation [lex.phases]
2.3 Character sets [lex.charset]
2.4 Trigraph sequences [lex.trigraph]
2.5 Preprocessing tokens [lex.pptoken]
2.6 Alternative tokens [lex.digraph]
2.7 Tokens [lex.token]
2.8 Comments [lex.comment]
2.9 Header names [lex.header]
2.10 Preprocessing numbers [lex.ppnumber]
2.11 Identifiers [lex.name]
2.12 Keywords [lex.key]
2.13 Operators and punctuators [lex.operators]
2.14 Literals [lex.literal]

2.5 Preprocessing tokens [lex.pptoken]

	Syntax (BNF) preprocessing-token: header-name identifier pp-number character-literal user-defined-character-literal string-literal user-defined-string-literal preprocessing-op-or-punc each non-white-space character that cannot be one of the above
1	Each preprocessing token that is converted to a token ([lex.token]) shall have the lexical form of a keyword, an identifier, a literal, an operator, or a punctuator.
2	A preprocessing token is the minimal lexical element of the language in translation phases 3 through 6. The categories of preprocessing token are: header names, identifiers, preprocessing numbers, character literals (including user-defined character literals), string literals (including user-defined string literals), preprocessing operators and punctuators, and single non-white-space characters that do not lexically match the other preprocessing token categories. If a ' or a " character matches the last category, the behavior is undefined. Preprocessing tokens can be separated by white space; this consists of comments ([lex.comment]), or white-space characters (space, horizontal tab, new-line, vertical tab, and form-feed), or both. As described in Clause [cpp], in certain circumstances during translation phase 4, white space (or the absence thereof) serves as more than preprocessing token separation. White space can appear within a preprocessing token only as part of a header name or between the quotation characters in a character literal or string literal.
3	If the input stream has been parsed into preprocessing tokens up to a given character:
(3.1)	If the next character begins a sequence of characters that could be the prefix and initial double quote of a raw string literal, such as R", the next preprocessing token shall be a raw string literal. Between the initial and final double quote characters of the raw string, any transformations performed in phases 1 and 2 (trigraphs, universal-character-names, and line splicing) are reverted; this reversion shall apply before any d-char, r-char, or delimiting parenthesis is identified. The raw string literal is defined as the shortest sequence of characters that matches the raw-string pattern encoding-prefixopt R raw-string
(3.2)	Otherwise, if the next three characters are <:: and the subsequent character is neither : nor >, the < is treated as a preprocessor token by itself and not as the first character of the alternative token <:.
(3.3)	Otherwise, the next preprocessing token is the longest sequence of characters that could constitute a preprocessing token, even if that would cause further lexical analysis to fail. Example #define R "x" const char* s = R"y"; // ill-formed raw string, not "x" "y"
4	ExampleThe program fragment 1Ex is parsed as a preprocessing number token (one that is not a valid floating or integer literal token), even though a parse as the pair of preprocessing tokens 1 and Ex might produce a valid expression (for example, if Ex were a macro defined as +1). Similarly, the program fragment 1E1 is parsed as a preprocessing number (one that is a valid floating literal token), whether or not E is a macro name.
5	ExampleThe program fragment x+++++y is parsed as x ++ ++ + y, which, if x and y have integral types, violates a constraint on increment operators, even though the parse x ++ + ++ y might yield a correct expression.

[edit]

Source: https://timsong-cpp.github.io/cppwp/n4659/lex.pptoken

List of Tables [tab]
List of Figures [fig]
1 Scope [intro.scope]
2 Normative references [intro.refs]
3 Terms and definitions [intro.defs]
4 General principles [intro]
5 Lexical conventions [lex]
5.1 Separate translation [lex.separate]
5.2 Phases of translation [lex.phases]
5.3 Character sets [lex.charset]
5.4 Preprocessing tokens [lex.pptoken]
5.5 Alternative tokens [lex.digraph]
5.6 Tokens [lex.token]
5.7 Comments [lex.comment]
5.8 Header names [lex.header]
5.9 Preprocessing numbers [lex.ppnumber]
5.10 Identifiers [lex.name]
5.11 Keywords [lex.key]
5.12 Operators and punctuators [lex.operators]
5.13 Literals [lex.literal]

5.4 Preprocessing tokens [lex.pptoken]

	Syntax (BNF) preprocessing-token: header-name identifier pp-number character-literal user-defined-character-literal string-literal user-defined-string-literal preprocessing-op-or-punc each non-white-space character that cannot be one of the above
1	Each preprocessing token that is converted to a token shall have the lexical form of a keyword, an identifier, a literal, an operator, or a punctuator.
2	A preprocessing token is the minimal lexical element of the language in translation phases 3 through 6. The categories of preprocessing token are: header names, identifiers, preprocessing numbers, character literals (including user-defined character literals), string literals (including user-defined string literals), preprocessing operators and punctuators, and single non-white-space characters that do not lexically match the other preprocessing token categories. If a ' or a " character matches the last category, the behavior is undefined. Preprocessing tokens can be separated by white space; this consists of comments, or white-space characters (space, horizontal tab, new-line, vertical tab, and form-feed), or both. As described in Clause [cpp], in certain circumstances during translation phase 4, white space (or the absence thereof) serves as more than preprocessing token separation. White space can appear within a preprocessing token only as part of a header name or between the quotation characters in a character literal or string literal.
3	If the input stream has been parsed into preprocessing tokens up to a given character:
(3.1)	If the next character begins a sequence of characters that could be the prefix and initial double quote of a raw string literal, such as R", the next preprocessing token shall be a raw string literal. Between the initial and final double quote characters of the raw string, any transformations performed in phases 1 and 2 (universal-character-names and line splicing) are reverted; this reversion shall apply before any d-char, r-char, or delimiting parenthesis is identified. The raw string literal is defined as the shortest sequence of characters that matches the raw-string pattern encoding-prefixopt R raw-string
(3.2)	Otherwise, if the next three characters are <​::​ and the subsequent character is neither : nor >, the < is treated as a preprocessing token by itself and not as the first character of the alternative token <:.
(3.3)	Otherwise, the next preprocessing token is the longest sequence of characters that could constitute a preprocessing token, even if that would cause further lexical analysis to fail, except that a header-name is only formed within a #include directive. Example #define R "x" const char* s = R"y"; // ill-formed raw string, not "x" "y"
4	ExampleThe program fragment 0xe+foo is parsed as a preprocessing number token (one that is not a valid floating or integer literal token), even though a parse as three preprocessing tokens 0xe, +, and foo might produce a valid expression (for example, if foo were a macro defined as 1). Similarly, the program fragment 1E1 is parsed as a preprocessing number (one that is a valid floating literal token), whether or not E is a macro name.
5	ExampleThe program fragment x+++++y is parsed as x ++ ++ + y, which, if x and y have integral types, violates a constraint on increment operators, even though the parse x ++ + ++ y might yield a correct expression.

[edit]

Source: https://timsong-cpp.github.io/cppwp/n4868/lex.pptoken

1 Scope [intro.scope]
2 Normative references [intro.refs]
3 Terms and definitions [intro.defs]
4 General principles [intro]
5 Lexical conventions [lex]
5.1 Separate translation [lex.separate]
5.2 Phases of translation [lex.phases]
5.3 Character sets [lex.charset]
5.4 Preprocessing tokens [lex.pptoken]
5.5 Alternative tokens [lex.digraph]
5.6 Tokens [lex.token]
5.7 Comments [lex.comment]
5.8 Header names [lex.header]
5.9 Preprocessing numbers [lex.ppnumber]
5.10 Identifiers [lex.name]
5.11 Keywords [lex.key]
5.12 Operators and punctuators [lex.operators]
5.13 Literals [lex.literal]

5.4 Preprocessing tokens [lex.pptoken]

	Syntax (BNF) preprocessing-token: header-name import-keyword module-keyword export-keyword identifier pp-number character-literal user-defined-character-literal string-literal user-defined-string-literal preprocessing-op-or-punc each non-whitespace character that cannot be one of the above
1	Each preprocessing token that is converted to a token shall have the lexical form of a keyword, an identifier, a literal, or an operator or punctuator.
2	A preprocessing token is the minimal lexical element of the language in translation phases 3 through 6. The categories of preprocessing token are: header names, placeholder tokens produced by preprocessing import and module directives (import-keyword, module-keyword, and export-keyword), identifiers, preprocessing numbers, character literals (including user-defined character literals), string literals (including user-defined string literals), preprocessing operators and punctuators, and single non-whitespace characters that do not lexically match the other preprocessing token categories. If a ' or a " character matches the last category, the behavior is undefined. Preprocessing tokens can be separated by whitespace; this consists of comments ([lex.comment]), or whitespace characters (space, horizontal tab, new-line, vertical tab, and form-feed), or both. As described in [cpp], in certain circumstances during translation phase 4, whitespace (or the absence thereof) serves as more than preprocessing token separation. White space can appear within a preprocessing token only as part of a header name or between the quotation characters in a character literal or string literal.
3	If the input stream has been parsed into preprocessing tokens up to a given character:
(3.1)	If the next character begins a sequence of characters that could be the prefix and initial double quote of a raw string literal, such as R", the next preprocessing token shall be a raw string literal. Between the initial and final double quote characters of the raw string, any transformations performed in phases 1 and 2 (universal-character-names and line splicing) are reverted; this reversion shall apply before any d-char, r-char, or delimiting parenthesis is identified. The raw string literal is defined as the shortest sequence of characters that matches the raw-string pattern encoding-prefixopt R raw-string
(3.2)	Otherwise, if the next three characters are <​::​ and the subsequent character is neither : nor >, the < is treated as a preprocessing token by itself and not as the first character of the alternative token <:.
(3.3)	Otherwise, the next preprocessing token is the longest sequence of characters that could constitute a preprocessing token, even if that would cause further lexical analysis to fail, except that a header-name ([lex.header]) is only formed
(3.3.1)	after the include or import preprocessing token in an #include ([cpp.include]) or import ([cpp.import]) directive, or
(3.3.2)	within a has-include-expression. Example #define R "x" const char* s = R"y"; // ill-formed raw string, not "x" "y"
4	The import-keyword is produced by processing an import directive ([cpp.import]), the module-keyword is produced by preprocessing a module directive ([cpp.module]), and the export-keyword is produced by preprocessing either of the previous two directives. NoteNone has any observable spelling.
5	ExampleThe program fragment 0xe+foo is parsed as a preprocessing number token (one that is not a valid integer-literal or floating-point-literal token), even though a parse as three preprocessing tokens 0xe, +, and foo might produce a valid expression (for example, if foo were a macro defined as 1). Similarly, the program fragment 1E1 is parsed as a preprocessing number (one that is a valid floating-point-literal token), whether or not E is a macro name.
6	ExampleThe program fragment x+++++y is parsed as x ++ ++ + y, which, if x and y have integral types, violates a constraint on increment operators, even though the parse x ++ + ++ y might yield a correct expression.

[edit]

Source: https://timsong-cpp.github.io/cppwp/n4950/lex.pptoken

1 Scope [intro.scope]
2 Normative references [intro.refs]
3 Terms and definitions [intro.defs]
4 General principles [intro]
5 Lexical conventions [lex]
5.1 Separate translation [lex.separate]
5.2 Phases of translation [lex.phases]
5.3 Character sets [lex.charset]
5.4 Preprocessing tokens [lex.pptoken]
5.5 Alternative tokens [lex.digraph]
5.6 Tokens [lex.token]
5.7 Comments [lex.comment]
5.8 Header names [lex.header]
5.9 Preprocessing numbers [lex.ppnumber]
5.10 Identifiers [lex.name]
5.11 Keywords [lex.key]
5.12 Operators and punctuators [lex.operators]
5.13 Literals [lex.literal]

5.4 Preprocessing tokens [lex.pptoken]

	Syntax (BNF) preprocessing-token: header-name import-keyword module-keyword export-keyword identifier pp-number character-literal user-defined-character-literal string-literal user-defined-string-literal preprocessing-op-or-punc each non-whitespace character that cannot be one of the above
1	Each preprocessing token that is converted to a token shall have the lexical form of a keyword, an identifier, a literal, or an operator or punctuator.
2	A preprocessing token is the minimal lexical element of the language in translation phases 3 through 6. In this document, glyphs are used to identify elements of the basic character set ([lex.charset]). The categories of preprocessing token are: header names, placeholder tokens produced by preprocessing import and module directives (import-keyword, module-keyword, and export-keyword), identifiers, preprocessing numbers, character literals (including user-defined character literals), string literals (including user-defined string literals), preprocessing operators and punctuators, and single non-whitespace characters that do not lexically match the other preprocessing token categories. If a U+0027 apostrophe or a U+0022 quotation mark character matches the last category, the behavior is undefined. If any character not in the basic character set matches the last category, the program is ill-formed. Preprocessing tokens can be separated by whitespace; this consists of comments ([lex.comment]), or whitespace characters (U+0020 space, U+0009 character tabulation, new-line, U+000b line tabulation, and U+000c form feed), or both. As described in [cpp], in certain circumstances during translation phase 4, whitespace (or the absence thereof) serves as more than preprocessing token separation. Whitespace can appear within a preprocessing token only as part of a header name or between the quotation characters in a character literal or string literal.
3	If the input stream has been parsed into preprocessing tokens up to a given character:
(3.1)	If the next character begins a sequence of characters that could be the prefix and initial double quote of a raw string literal, such as R", the next preprocessing token shall be a raw string literal. Between the initial and final double quote characters of the raw string, any transformations performed in phase 2 (line splicing) are reverted; this reversion shall apply before any d-char, r-char, or delimiting parenthesis is identified. The raw string literal is defined as the shortest sequence of characters that matches the raw-string pattern encoding-prefixopt R raw-string
(3.2)	Otherwise, if the next three characters are <​::​ and the subsequent character is neither : nor >, the < is treated as a preprocessing token by itself and not as the first character of the alternative token <:.
(3.3)	Otherwise, the next preprocessing token is the longest sequence of characters that could constitute a preprocessing token, even if that would cause further lexical analysis to fail, except that a header-name ([lex.header]) is only formed
(3.3.1)	after the include or import preprocessing token in an #include ([cpp.include]) or import ([cpp.import]) directive, or
(3.3.2)	within a has-include-expression. Example  #define R "x" const char* s = R"y"; // ill-formed raw string, not "x" "y"
4	The import-keyword is produced by processing an import directive ([cpp.import]), the module-keyword is produced by preprocessing a module directive ([cpp.module]), and the export-keyword is produced by preprocessing either of the previous two directives. NoteNone has any observable spelling.
5	Example The program fragment 0xe+foo is parsed as a preprocessing number token (one that is not a valid integer-literal or floating-point-literal token), even though a parse as three preprocessing tokens 0xe, +, and foo can produce a valid expression (for example, if foo is a macro defined as 1). Similarly, the program fragment 1E1 is parsed as a preprocessing number (one that is a valid floating-point-literal token), whether or not E is a macro name.
6	Example The program fragment x+++++y is parsed as x ++ ++ + y, which, if x and y have integral types, violates a constraint on increment operators, even though the parse x ++ + ++ y can yield a correct expression.