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-rw-r--r--libbuild2/lexer.hxx46
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())?