// Substitutes values, calculated by callback, on matching regex
func (c *Config) computeVar(beforeValue *string, regx *regexp.Regexp, headsz, tailsz int, withVar func(*string) string) (*string, error) {
var i int
computedVal := beforeValue
for i = 0; i < _DEPTH_VALUES; i++ { // keep a sane depth
vr := regx.FindStringSubmatchIndex(*computedVal)
if len(vr) == 0 {
break
}
varname := (*computedVal)[vr[headsz]:vr[headsz+1]]
varVal := withVar(&varname)
if varVal == "" {
return &varVal, errors.New(fmt.Sprintf("Option not found: %s", varname))
}
// substitute by new value and take off leading '%(' and trailing ')s'
// %(foo)s => headsz=2, tailsz=2
// ${foo} => headsz=2, tailsz=1
newVal := (*computedVal)[0:vr[headsz]-headsz] + varVal + (*computedVal)[vr[headsz+1]+tailsz:]
computedVal = &newVal
}
if i == _DEPTH_VALUES {
retVal := ""
return &retVal,
fmt.Errorf("Possible cycle while unfolding variables: max depth of %d reached", _DEPTH_VALUES)
}
return computedVal, nil
}
// consume searches for r in the remaining text. If found, it consumes
// up to the end of the match, fills m.groups with the matched groups,
// and returns true.
func (m *matcher) consume(r *regexp.Regexp) bool {
idx := r.FindStringSubmatchIndex(m.str[m.pos:])
if idx == nil {
m.groups = m.groups[:0]
return false
}
if len(idx)/2 <= cap(m.groups) {
m.groups = m.groups[:len(idx)/2]
} else {
m.groups = make([]string, len(idx)/2, len(idx))
}
for i := range m.groups {
if idx[i*2] >= 0 {
m.groups[i] = m.str[m.pos+idx[i*2] : m.pos+idx[i*2+1]]
} else {
m.groups[i] = ""
}
}
m.matchPos = m.pos + idx[0]
m.pos += idx[1]
return true
}