User:Code-Analysis/sandbox
The grammar of any programming language can be considered either in wide terms that include exact specification of everything what is allowed and what is not allowed in the language or in narrow terms that describe only the formal grammar that is suitable for automatic creation of LR parsers. This article focuses on the formal grammar. General description of the C++ language can be found in the main article.
Formal grammar describes the `context free grammar` of the language. It lacks various restrictions like requirement for all variables to be defined; formal grammar cannot distinguish between the name of the variable and the name of the type. All identifiers for LR parser are simply identifiers. Information about identifiers is stored in the name tables. Name tables are not part of the formal grammar. Nevertheless sometimes LR parser has to make decision on the nature of the identifier. This decision shows up as resolution of the grammar conflict.
C++ 2003 Grammar
The formal grammar of the language is presented in the Annex A of the standard. It consists of 3 major parts.
Lexical conventions
This part of the grammar describes what is an identifier, number, string, etc. Some of the rules are vague and contain human language like `each non-white-space character that cannot be ...` or `any member of the source character set except ...`. Other rules contain lengthy enumerations that mention all letters of the English alphabet or names of all possible operations. This is why the table below contains 2 separate lines for the number of rules. The first line counts lengthy enumeration as one rule. The second line counts all rules of the section.
| Non terminals | 42 |
| Grammar rules (significantly different) | 94 |
| Grammar rules all | 276 |
External links
Links to C++ grammars that can be used in compiler generation tools.
- C-36.html - Information on C++ grammar by Jim Roskind (a better link might be needed).
- GraCpp_StndGrammar.php – The C++ 2003 grammar as it appears in the standard.
- GraCpp_EvenGrammar.php – Optimized C++ 2003 grammar for using in autogenerated LR parsers.