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Diffstat (limited to 'conf/cf-lex.l')
| -rw-r--r-- | conf/cf-lex.l | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/conf/cf-lex.l b/conf/cf-lex.l index e7cb2c8a..8f8fcfbd 100644 --- a/conf/cf-lex.l +++ b/conf/cf-lex.l @@ -424,3 +424,35 @@ cf_symbol_class_name(struct symbol *sym) return "unknown type"; } } + + +/** + * DOC: Parser + * + * Both the configuration and CLI commands are analysed using a syntax + * driven parser generated by the |bison| tool from a grammar which + * is constructed from information gathered from grammar snippets by + * the |gen_parser.m4| script. + * + * Grammar snippets are files (usually with extension |.Y|) contributed + * by various BIRD modules to provide information about syntax of their + * configuration and their CLI commands. Each snipped consists of several + * section, each of them starting with a special keyword: |CF_HDR| for + * a list of |#include| directives needed by the C code, |CF_DEFINES| + * for a list of C declarations, |CF_DECLS| for |bison| declarations + * including keyword definitions specified as |CF_KEYWORDS|, |CF_GRAMMAR| + * for the grammar rules, |CF_CODE| for auxillary C code and finally + * |CF_END| at the end of the snippet. + * + * To create references between the snippets, it's possible to define + * multi-part rules by utilizing the |CF_ADDTO| macro which adds a new + * alternative to a multi-part rule. + * + * CLI commands are defined using a |CF_CLI| macro. Its parameters are: + * the list of keywords determining the command, the list of paramaters, + * help text for the parameters and help text for the command. + * + * Values of |enum| filter types can be defined using |CF_ENUM| with + * the following parameters: name of filter type, prefix common for all + * literals of this type, names of all the possible values. + */ |