regexp: add SubexpNames
Fixes #2440.
R=r, dsymonds
CC=golang-dev
https://golang.org/cl/5559043
diff --git a/src/pkg/regexp/all_test.go b/src/pkg/regexp/all_test.go
index e729510..107dfe3 100644
--- a/src/pkg/regexp/all_test.go
+++ b/src/pkg/regexp/all_test.go
@@ -289,30 +289,45 @@
}
}
-type numSubexpCase struct {
- input string
- expected int
+type subexpCase struct {
+ input string
+ num int
+ names []string
}
-var numSubexpCases = []numSubexpCase{
- {``, 0},
- {`.*`, 0},
- {`abba`, 0},
- {`ab(b)a`, 1},
- {`ab(.*)a`, 1},
- {`(.*)ab(.*)a`, 2},
- {`(.*)(ab)(.*)a`, 3},
- {`(.*)((a)b)(.*)a`, 4},
- {`(.*)(\(ab)(.*)a`, 3},
- {`(.*)(\(a\)b)(.*)a`, 3},
+var subexpCases = []subexpCase{
+ {``, 0, nil},
+ {`.*`, 0, nil},
+ {`abba`, 0, nil},
+ {`ab(b)a`, 1, []string{"", ""}},
+ {`ab(.*)a`, 1, []string{"", ""}},
+ {`(.*)ab(.*)a`, 2, []string{"", "", ""}},
+ {`(.*)(ab)(.*)a`, 3, []string{"", "", "", ""}},
+ {`(.*)((a)b)(.*)a`, 4, []string{"", "", "", "", ""}},
+ {`(.*)(\(ab)(.*)a`, 3, []string{"", "", "", ""}},
+ {`(.*)(\(a\)b)(.*)a`, 3, []string{"", "", "", ""}},
+ {`(?P<foo>.*)(?P<bar>(a)b)(?P<foo>.*)a`, 4, []string{"", "foo", "bar", "", "foo"}},
}
-func TestNumSubexp(t *testing.T) {
- for _, c := range numSubexpCases {
+func TestSubexp(t *testing.T) {
+ for _, c := range subexpCases {
re := MustCompile(c.input)
n := re.NumSubexp()
- if n != c.expected {
- t.Errorf("NumSubexp for %q returned %d, expected %d", c.input, n, c.expected)
+ if n != c.num {
+ t.Errorf("%q: NumSubexp = %d, want %d", c.input, n, c.num)
+ continue
+ }
+ names := re.SubexpNames()
+ if len(names) != 1+n {
+ t.Errorf("%q: len(SubexpNames) = %d, want %d", c.input, len(names), n)
+ continue
+ }
+ if c.names != nil {
+ for i := 0; i < 1+n; i++ {
+ if names[i] != c.names[i] {
+ t.Errorf("%q: SubexpNames[%d] = %q, want %q", c.input, i, names[i], c.names[i])
+ }
+ }
}
}
}
diff --git a/src/pkg/regexp/regexp.go b/src/pkg/regexp/regexp.go
index b0c6a0b..c161acd 100644
--- a/src/pkg/regexp/regexp.go
+++ b/src/pkg/regexp/regexp.go
@@ -85,6 +85,7 @@
prefixRune rune // first rune in prefix
cond syntax.EmptyOp // empty-width conditions required at start of match
numSubexp int
+ subexpNames []string
longest bool
// cache of machines for running regexp
@@ -140,17 +141,20 @@
return nil, err
}
maxCap := re.MaxCap()
+ capNames := re.CapNames()
+
re = re.Simplify()
prog, err := syntax.Compile(re)
if err != nil {
return nil, err
}
regexp := &Regexp{
- expr: expr,
- prog: prog,
- numSubexp: maxCap,
- cond: prog.StartCond(),
- longest: longest,
+ expr: expr,
+ prog: prog,
+ numSubexp: maxCap,
+ subexpNames: capNames,
+ cond: prog.StartCond(),
+ longest: longest,
}
regexp.prefix, regexp.prefixComplete = prog.Prefix()
if regexp.prefix != "" {
@@ -223,6 +227,15 @@
return re.numSubexp
}
+// SubexpNames returns the names of the parenthesized subexpressions
+// in this Regexp. The name for the first sub-expression is names[1],
+// so that if m is a match slice, the name for m[i] is SubexpNames()[i].
+// Since the Regexp as a whole cannot be named, names[0] is always
+// the empty string. The slice should not be modified.
+func (re *Regexp) SubexpNames() []string {
+ return re.subexpNames
+}
+
const endOfText rune = -1
// input abstracts different representations of the input text. It provides
diff --git a/src/pkg/regexp/syntax/regexp.go b/src/pkg/regexp/syntax/regexp.go
index adcfe29..668a077 100644
--- a/src/pkg/regexp/syntax/regexp.go
+++ b/src/pkg/regexp/syntax/regexp.go
@@ -303,3 +303,19 @@
}
return m
}
+
+// CapNames walks the regexp to find the names of capturing groups.
+func (re *Regexp) CapNames() []string {
+ names := make([]string, re.MaxCap()+1)
+ re.capNames(names)
+ return names
+}
+
+func (re *Regexp) capNames(names []string) {
+ if re.Op == OpCapture {
+ names[re.Cap] = re.Name
+ }
+ for _, sub := range re.Sub {
+ sub.capNames(names)
+ }
+}
