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authorBoris Kolpackov <boris@codesynthesis.com>2022-04-06 11:26:52 +0200
committerBoris Kolpackov <boris@codesynthesis.com>2022-04-06 13:51:56 +0200
commit76be0a35f6c37cda7ba65530330f1ac246fb52a8 (patch)
treef613ceafcf6c7208984d4536653061c4e0c23be7 /libbuild2/rule.hxx
parent0a9dd0c7d31cbba2170fdfda4b747a1fe5ce665a (diff)
Add support for rule hints
A rule hint is a target attribute, for example: [rule_hint=cxx] exe{hello}: c{hello} Rule hints can be used to resolve ambiguity when multiple rules match the same target as well as to override an unambiguous match.
Diffstat (limited to 'libbuild2/rule.hxx')
-rw-r--r--libbuild2/rule.hxx50
1 files changed, 40 insertions, 10 deletions
diff --git a/libbuild2/rule.hxx b/libbuild2/rule.hxx
index 73492fe..1429ab2 100644
--- a/libbuild2/rule.hxx
+++ b/libbuild2/rule.hxx
@@ -24,6 +24,10 @@ namespace build2
//
// Note: match() is only called once but may not be followed by apply().
//
+ // The hint argument is the rule hint, if any, that was used to select this
+ // rule. While normally not factored into the match decision, a rule may
+ // "try harder" if a hint was specified (see cc::link_rule for an example).
+ //
// The match_extra argument (the type is defined in target.hxx) is used to
// pass additional information that is only needed by some rule
// implementations. It is also a way for us to later pass more information
@@ -47,15 +51,29 @@ namespace build2
rule (const rule&) = delete;
rule& operator= (const rule&) = delete;
+
+ // Sometimes we want to match only if another rule of ours would match
+ // another operation. For example, we would want our install rule to match
+ // only if our update rule also matches.
+ //
+ // Arranging this, however, is not a simple matter of calling the other
+ // rule's match(): we also have to take into account the rule hints for
+ // that operation. This helper performs all the necessary steps. Note:
+ // should only be called from match() (see target::find_hint() for
+ // details).
+ //
+ bool
+ sub_match (const string& rule_name, operation_id hint_op,
+ action, target&, match_extra&) const;
};
- // Simplified interface for rules that don't care about the extras.
+ // Simplified interface for rules that don't care about the hint or extras.
//
class LIBBUILD2_SYMEXPORT simple_rule: public rule
{
public:
virtual bool
- match (action, target&, const string& hint) const = 0;
+ match (action, target&) const = 0;
virtual recipe
apply (action, target&) const = 0;
@@ -65,19 +83,31 @@ namespace build2
virtual recipe
apply (action, target&, match_extra&) const override;
+
+ // The simplified version of sub_match() above.
+ //
+ // Note that it calls the simplified match() directly rather than going
+ // through the original.
+ //
+ bool
+ sub_match (const string& rule_name, operation_id hint_op,
+ action, target&) const;
};
// Fallback rule that only matches if the file exists. It will also match
// an mtime_target provided it has a set timestamp.
//
- class LIBBUILD2_SYMEXPORT file_rule: public simple_rule
+ // Note: this rule is "hot" because it matches every static source file and
+ // so we don't use simple_rule to avoid two extra virtual calls.
+ //
+ class LIBBUILD2_SYMEXPORT file_rule: public rule
{
public:
virtual bool
- match (action, target&, const string&) const override;
+ match (action, target&, const string&, match_extra&) const override;
virtual recipe
- apply (action, target&) const override;
+ apply (action, target&, match_extra&) const override;
file_rule () {}
@@ -89,7 +119,7 @@ namespace build2
{
public:
virtual bool
- match (action, target&, const string&) const override;
+ match (action, target&) const override;
virtual recipe
apply (action, target&) const override;
@@ -105,7 +135,7 @@ namespace build2
{
public:
virtual bool
- match (action, target&, const string&) const override;
+ match (action, target&) const override;
virtual recipe
apply (action, target&) const override;
@@ -132,7 +162,7 @@ namespace build2
{
public:
virtual bool
- match (action, target&, const string&) const override;
+ match (action, target&) const override;
virtual recipe
apply (action, target&) const override;
@@ -219,8 +249,8 @@ namespace build2
// Implementation details.
//
public:
- // The name in rule_match is used as a hint and as a name in diagnostics.
- // The former does not apply to ad hoc recipes (but does apply to ad hoc
+ // The name in rule_match is used to match hints and in diagnostics. The
+ // former does not apply to ad hoc recipes (but does apply to ad hoc
// rules).
//
const build2::rule_match rule_match;