diff options
Diffstat (limited to 'libbuild2/lexer.hxx')
| -rw-r--r-- | libbuild2/lexer.hxx | 46 |
1 files changed, 31 insertions, 15 deletions
diff --git a/libbuild2/lexer.hxx b/libbuild2/lexer.hxx index 59debc4..715926c 100644 --- a/libbuild2/lexer.hxx +++ b/libbuild2/lexer.hxx @@ -21,28 +21,29 @@ namespace build2 { // Context-dependent lexing mode. Quoted modes are internal and should not // be set explicitly. In the value mode we don't treat certain characters - // (e.g., '+', '=') as special so that we can use them in the variable - // values, e.g., 'foo = g++'. In contrast, in the variable mode, we restrict - // certain character (e.g., '/') from appearing in the name. The values mode - // is like value but recogizes ',' as special (used in contexts where we - // need to list multiple values). The attribute mode is also like value - // except it doesn't treat '{' and '}' as special (so we cannot have name - // groups in attributes). The eval mode is used in the evaluation context. + // (e.g., `+`, `=`) as special so that we can use them in the variable + // values, e.g., `foo = g++`. In contrast, in the variable mode, we restrict + // certain character (e.g., `/`) from appearing in the name. The values mode + // is like value but recogizes `,` as special (used in contexts where we + // need to list multiple values). The attributes mode is also like value + // except it doesn't treat `{` and `}` as special (so we cannot have name + // groups in attributes) and recognizes the closing `]`. The eval mode is + // used in the evaluation context. // // A number of modes are "derived" from the value/values mode by recognizing // a few extra characters: // // switch_expressions values plus `:` - // case_patterns values plus '|' and ':' + // case_patterns values plus `|` and `:` // // Note that the normal, value/values and derived, as well as eval modes // split words separated by the pair character (to disable pairs one can - // pass '\0' as a pair character). + // pass `\0` as a pair character). // // The alternative modes must be set manually. The value/values and derived // modes automatically expires after the end of the line. The attribute mode - // expires after the closing ']'. The variable mode expires after the word - // token. And the eval mode expires after the closing ')'. + // expires after the closing `]`. The variable mode expires after the word + // token. And the eval mode expires after the closing `)`. // // Note that normally it is only safe to switch mode when the current token // is not quoted (or, more generally, when you are not in the double-quoted @@ -50,6 +51,15 @@ namespace build2 // variable name mode). Failed that your mode (which now will be the top of // the mode stack) will prevent proper recognition of the closing quote. // + // Finally, attributes recognition (the `[` token) cuts across most of the + // modes and is handled with a flag. In the normal mode it is automatically + // set at the beginning and after each newline. In all other modes it must + // be explicitly set at points where attributes are recognized. In all the + // cases it is automatically reset after lexing the next token (whether `[` + // or not). + // + // @@ Maybe also enable at the beginning of value? + // // Extendable/inheritable enum-like class. // @@ -65,7 +75,7 @@ namespace build2 values, case_patterns, switch_expressions, - attribute, + attributes, eval, single_quoted, double_quoted, @@ -97,15 +107,20 @@ namespace build2 name () const {return name_;} // Note: sets mode for the next token. The second argument can be used to - // specifythe pair separator character (if the mode supports pairs). If - // escapes not specified, then inherit the current mode's (thought a mode - // can also override it). + // specify the pair separator character (if the mode supports pairs). If + // escapes is not specified, then inherit the current mode's (though a + // mode can also override it). // virtual void mode (lexer_mode, char pair_separator = '\0', optional<const char*> escapes = nullopt); + // Enable attributes recognition for the next token. + // + void + enable_attributes () {state_.top ().attributes = true;} + // Expire the current mode early. // void @@ -136,6 +151,7 @@ namespace build2 struct state { lexer_mode mode; + bool attributes; char sep_pair; bool sep_space; // Are whitespaces separators (see skip_spaces())? |