3 Syntax Notation

We use an extended BNF grammar to describe the syntax of Larch/C++. The extensions are as follows [Ledgard80].

• Nonterminal symbols are written as follows: nonterminal. That is, nonterminal symbols appear in an italic font (in the printed manual).
• Terminal symbols are written as follows: terminal. In a few cases it is also necessary to quote terminal symbols, such as when using `|' as a terminal symbol instead of a meta-symbol (see section 4.10 Special Symbols).
• Square brackets ([ and ]) surround optional text. Note that [ and ] are terminals.
• The notation ... means that the preceding nonterminal or group of optional text can be repeated zero (0) or more times.

For example, the following gives a production for a non-empty list of init-declarators, separated by commas.

init-declarator-list ::= init-declarator [ , init-declarator ] ...

To remind the reader that the notation `...' means zero or more repetitions, we try to use `...' only following optional text, although in cases such as the following the brackets and the enclosed nonterminal could have been omitted.

type-specifier-seq ::= type-specifier [ type-specifier ] ...

As in the above examples, we follow the evolving C++ standard [ANSI95] in using nonterminal names of the form X-list to mean a comma-separated list, and nonterminal names of the form X-seq to mean a sequence not separated by commas.

We use "//" to start a comment (to you, the reader) in the grammar.

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