C # Language Specification--2.2.1 grammatical notation

Specification

The lexical-French and syntactic-French methods are expressed in terms of grammatical production. Each grammar-generation defines a non-closing symbol and its possible extension (a sequence consisting of a non-terminator or terminator). In the grammar-generation, the non-closing symbol appears italic, and the ending symbol is displayed as a width font.

The first line of the grammar-generation is the name of the non-closing symbol defined by the formula, followed by a colon. Each subsequent indent lists a possible extension, which is given in the form of a sequence consisting of a non-terminator or terminator. For example, the production type:

While-statement: (While statement:)

while (boolean-expression) Embedded-statement (a while (Boolean expression) embedded statement)

Defines a while statement, which is composed of a tag while beginning, followed by a tag "(", Boolean expression, Tag "), and an embedded statement.

Lists these possible extensions (one row for each extension) when there is a possible non-end symbol extension. For example, the production type:

Statement-list: (statement list:)

Statement (statement)

Statement-list statement (statement list statement)

Defines a statement list that contains only one statement, or consists of a statement list and a statement followed by it. In other words, the definition is recursive, and the statement list consists of one or more statements.

A symbol is optional if the following prefix is labeled "optional". Production Type:

Block: (blocks:)

{statement-listopt} ({statement list optional})

is a short form of the following generation:

Block: (blocks:)

{   }

{Statement-list} ({statement list})

It defines a block that consists of an optional list of statements enclosed in "{" and "}" tags.

Options are usually listed on separate lines, but when there are many options, you can precede the extended list given on a single line with the phrase "one of the following." This simply lists the short form of each option on a separate line. For example, the production type:

Real-type-suffix:one of (real type suffix: one of the following)

F F D D m

is a short form of the following generation:

Real-type-suffix: (Real type suffix:)

F
F
D
D
M
M