From 86bdbfbf45a0c13aca146955a3325207ebd66c75 Mon Sep 17 00:00:00 2001
From: Arran Walker <arran.walker@fiveturns.org>
Date: Tue, 23 Apr 2019 10:50:46 +0000
Subject: plumbing: format/gitattributes support

Implements gitattributes parsing, matching and attribute extraction.

Signed-off-by: Arran Walker <arran.walker@fiveturns.org>
---
 plumbing/format/gitattributes/matcher.go | 78 ++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 plumbing/format/gitattributes/matcher.go

(limited to 'plumbing/format/gitattributes/matcher.go')

diff --git a/plumbing/format/gitattributes/matcher.go b/plumbing/format/gitattributes/matcher.go
new file mode 100644
index 0000000..df12864
--- /dev/null
+++ b/plumbing/format/gitattributes/matcher.go
@@ -0,0 +1,78 @@
+package gitattributes
+
+// Matcher defines a global multi-pattern matcher for gitattributes patterns
+type Matcher interface {
+	// Match matches patterns in the order of priorities.
+	Match(path []string, attributes []string) (map[string]Attribute, bool)
+}
+
+type MatcherOptions struct{}
+
+// NewMatcher constructs a new matcher. Patterns must be given in the order of
+// increasing priority. That is the most generic settings files first, then the
+// content of the repo .gitattributes, then content of .gitattributes down the
+// path.
+func NewMatcher(stack []MatchAttribute) Matcher {
+	m := &matcher{stack: stack}
+	m.init()
+
+	return m
+}
+
+type matcher struct {
+	stack  []MatchAttribute
+	macros map[string]MatchAttribute
+}
+
+func (m *matcher) init() {
+	m.macros = make(map[string]MatchAttribute)
+
+	for _, attr := range m.stack {
+		if attr.Pattern == nil {
+			m.macros[attr.Name] = attr
+		}
+	}
+}
+
+// Match matches path against the patterns in gitattributes files and returns
+// the attributes associated with the path.
+//
+// Specific attributes can be specified otherwise all attributes are returned.
+//
+// Matched is true if any path was matched to a rule, even if the results map
+// is empty.
+func (m *matcher) Match(path []string, attributes []string) (results map[string]Attribute, matched bool) {
+	results = make(map[string]Attribute, len(attributes))
+
+	n := len(m.stack)
+	for i := n - 1; i >= 0; i-- {
+		if len(attributes) > 0 && len(attributes) == len(results) {
+			return
+		}
+
+		pattern := m.stack[i].Pattern
+		if pattern == nil {
+			continue
+		}
+
+		if match := pattern.Match(path); match {
+			matched = true
+			for _, attr := range m.stack[i].Attributes {
+				if attr.IsSet() {
+					m.expandMacro(attr.Name(), results)
+				}
+				results[attr.Name()] = attr
+			}
+		}
+	}
+	return
+}
+
+func (m *matcher) expandMacro(name string, results map[string]Attribute) bool {
+	if macro, ok := m.macros[name]; ok {
+		for _, attr := range macro.Attributes {
+			results[attr.Name()] = attr
+		}
+	}
+	return false
+}
-- 
cgit