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param.go
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param.go
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// Copyright (c) 2017, Daniel Martí <mvdan@mvdan.cc>
// See LICENSE for licensing information
package expand
import (
"fmt"
"regexp"
"slices"
"strconv"
"strings"
"unicode"
"unicode/utf8"
"mvdan.cc/sh/v3/pattern"
"mvdan.cc/sh/v3/syntax"
)
func nodeLit(node syntax.Node) string {
if word, ok := node.(*syntax.Word); ok {
return word.Lit()
}
return ""
}
type UnsetParameterError struct {
Node *syntax.ParamExp
Message string
}
func (u UnsetParameterError) Error() string {
return fmt.Sprintf("%s: %s", u.Node.Param.Value, u.Message)
}
func overridingUnset(pe *syntax.ParamExp) bool {
if pe.Exp == nil {
return false
}
switch pe.Exp.Op {
case syntax.AlternateUnset, syntax.AlternateUnsetOrNull,
syntax.DefaultUnset, syntax.DefaultUnsetOrNull,
syntax.ErrorUnset, syntax.ErrorUnsetOrNull,
syntax.AssignUnset, syntax.AssignUnsetOrNull:
return true
}
return false
}
func (cfg *Config) paramExp(pe *syntax.ParamExp) (string, error) {
oldParam := cfg.curParam
cfg.curParam = pe
defer func() { cfg.curParam = oldParam }()
name := pe.Param.Value
index := pe.Index
switch name {
case "@", "*":
index = &syntax.Word{Parts: []syntax.WordPart{
&syntax.Lit{Value: name},
}}
}
var vr Variable
switch name {
case "LINENO":
// This is the only parameter expansion that the environment
// interface cannot satisfy.
line := uint64(cfg.curParam.Pos().Line())
vr = Variable{Kind: String, Str: strconv.FormatUint(line, 10)}
default:
vr = cfg.Env.Get(name)
}
orig := vr
_, vr = vr.Resolve(cfg.Env)
if cfg.NoUnset && vr.Kind == Unset && !overridingUnset(pe) {
return "", UnsetParameterError{
Node: pe,
Message: "unbound variable",
}
}
var sliceOffset, sliceLen int
if pe.Slice != nil {
var err error
if pe.Slice.Offset != nil {
sliceOffset, err = Arithm(cfg, pe.Slice.Offset)
if err != nil {
return "", err
}
}
if pe.Slice.Length != nil {
sliceLen, err = Arithm(cfg, pe.Slice.Length)
if err != nil {
return "", err
}
}
}
var (
str string
elems []string
indexAllElements bool // true if var has been accessed with * or @ index
callVarInd = true
)
switch nodeLit(index) {
case "@", "*":
switch vr.Kind {
case Unset:
elems = nil
indexAllElements = true
case Indexed:
indexAllElements = true
callVarInd = false
elems = vr.List
slicePos := func(n int) int {
if n < 0 {
n = len(elems) + n
if n < 0 {
n = len(elems)
}
} else if n > len(elems) {
n = len(elems)
}
return n
}
if pe.Slice != nil && pe.Slice.Offset != nil {
elems = elems[slicePos(sliceOffset):]
}
if pe.Slice != nil && pe.Slice.Length != nil {
elems = elems[:slicePos(sliceLen)]
}
str = strings.Join(elems, " ")
}
}
if callVarInd {
var err error
str, err = cfg.varInd(vr, index)
if err != nil {
return "", err
}
}
if !indexAllElements {
elems = []string{str}
}
switch {
case pe.Length:
n := len(elems)
switch nodeLit(index) {
case "@", "*":
default:
n = utf8.RuneCountInString(str)
}
str = strconv.Itoa(n)
case pe.Excl:
var strs []string
switch {
case pe.Names != 0:
strs = cfg.namesByPrefix(pe.Param.Value)
case orig.Kind == NameRef:
strs = append(strs, orig.Str)
case pe.Index != nil && vr.Kind == Indexed:
for i, e := range vr.List {
if e != "" {
strs = append(strs, strconv.Itoa(i))
}
}
case pe.Index != nil && vr.Kind == Associative:
// TODO: use maps.Keys
for k := range vr.Map {
strs = append(strs, k)
}
case vr.Kind == Unset:
return "", fmt.Errorf("invalid indirect expansion")
case str == "":
return "", nil
default:
vr = cfg.Env.Get(str)
strs = append(strs, vr.String())
}
slices.Sort(strs)
str = strings.Join(strs, " ")
case pe.Slice != nil:
if callVarInd {
slicePos := func(n int) int {
if n < 0 {
n = len(str) + n
if n < 0 {
n = len(str)
}
} else if n > len(str) {
n = len(str)
}
return n
}
if pe.Slice.Offset != nil {
str = str[slicePos(sliceOffset):]
}
if pe.Slice.Length != nil {
str = str[:slicePos(sliceLen)]
}
} // else, elems are already sliced
case pe.Repl != nil:
orig, err := Pattern(cfg, pe.Repl.Orig)
if err != nil {
return "", err
}
if orig == "" {
break // nothing to replace
}
with, err := Literal(cfg, pe.Repl.With)
if err != nil {
return "", err
}
n := 1
if pe.Repl.All {
n = -1
}
locs := findAllIndex(orig, str, n)
buf := cfg.strBuilder()
last := 0
for _, loc := range locs {
buf.WriteString(str[last:loc[0]])
buf.WriteString(with)
last = loc[1]
}
buf.WriteString(str[last:])
str = buf.String()
case pe.Exp != nil:
arg, err := Literal(cfg, pe.Exp.Word)
if err != nil {
return "", err
}
switch op := pe.Exp.Op; op {
case syntax.AlternateUnsetOrNull:
if str == "" {
break
}
fallthrough
case syntax.AlternateUnset:
if vr.IsSet() {
str = arg
}
case syntax.DefaultUnset:
if vr.IsSet() {
break
}
fallthrough
case syntax.DefaultUnsetOrNull:
if str == "" {
str = arg
}
case syntax.ErrorUnset:
if vr.IsSet() {
break
}
fallthrough
case syntax.ErrorUnsetOrNull:
if str == "" {
return "", UnsetParameterError{
Node: pe,
Message: arg,
}
}
case syntax.AssignUnset:
if vr.IsSet() {
break
}
fallthrough
case syntax.AssignUnsetOrNull:
if str == "" {
if err := cfg.envSet(name, arg); err != nil {
return "", err
}
str = arg
}
case syntax.RemSmallPrefix, syntax.RemLargePrefix,
syntax.RemSmallSuffix, syntax.RemLargeSuffix:
suffix := op == syntax.RemSmallSuffix || op == syntax.RemLargeSuffix
small := op == syntax.RemSmallPrefix || op == syntax.RemSmallSuffix
for i, elem := range elems {
elems[i] = removePattern(elem, arg, suffix, small)
}
str = strings.Join(elems, " ")
case syntax.UpperFirst, syntax.UpperAll,
syntax.LowerFirst, syntax.LowerAll:
caseFunc := unicode.ToLower
if op == syntax.UpperFirst || op == syntax.UpperAll {
caseFunc = unicode.ToUpper
}
all := op == syntax.UpperAll || op == syntax.LowerAll
// empty string means '?'; nothing to do there
expr, err := pattern.Regexp(arg, 0)
if err != nil {
return str, nil
}
rx := regexp.MustCompile(expr)
for i, elem := range elems {
rs := []rune(elem)
for ri, r := range rs {
if rx.MatchString(string(r)) {
rs[ri] = caseFunc(r)
if !all {
break
}
}
}
elems[i] = string(rs)
}
str = strings.Join(elems, " ")
case syntax.OtherParamOps:
switch arg {
case "Q":
str, err = syntax.Quote(str, syntax.LangBash)
if err != nil {
// Is this even possible? If a user runs into this panic,
// it's most likely a bug we need to fix.
panic(err)
}
case "E":
tail := str
var rns []rune
for tail != "" {
var rn rune
rn, _, tail, _ = strconv.UnquoteChar(tail, 0)
rns = append(rns, rn)
}
str = string(rns)
case "P", "A", "a":
panic(fmt.Sprintf("unhandled @%s param expansion", arg))
default:
panic(fmt.Sprintf("unexpected @%s param expansion", arg))
}
}
}
return str, nil
}
func removePattern(str, pat string, fromEnd, shortest bool) string {
var mode pattern.Mode
if shortest {
mode |= pattern.Shortest
}
expr, err := pattern.Regexp(pat, mode)
if err != nil {
return str
}
switch {
case fromEnd && shortest:
// use .* to get the right-most shortest match
expr = ".*(" + expr + ")$"
case fromEnd:
// simple suffix
expr = "(" + expr + ")$"
default:
// simple prefix
expr = "^(" + expr + ")"
}
// no need to check error as Translate returns one
rx := regexp.MustCompile(expr)
if loc := rx.FindStringSubmatchIndex(str); loc != nil {
// remove the original pattern (the submatch)
str = str[:loc[2]] + str[loc[3]:]
}
return str
}
func (cfg *Config) varInd(vr Variable, idx syntax.ArithmExpr) (string, error) {
if idx == nil {
return vr.String(), nil
}
switch vr.Kind {
case String:
n, err := Arithm(cfg, idx)
if err != nil {
return "", err
}
if n == 0 {
return vr.Str, nil
}
case Indexed:
switch nodeLit(idx) {
case "*", "@":
return strings.Join(vr.List, " "), nil
}
i, err := Arithm(cfg, idx)
if err != nil {
return "", err
}
if i < 0 {
return "", fmt.Errorf("negative array index")
}
if i < len(vr.List) {
return vr.List[i], nil
}
case Associative:
switch lit := nodeLit(idx); lit {
case "@", "*":
strs := make([]string, 0, len(vr.Map))
// TODO: use maps.Values
for _, val := range vr.Map {
strs = append(strs, val)
}
slices.Sort(strs)
if lit == "*" {
return cfg.ifsJoin(strs), nil
}
return strings.Join(strs, " "), nil
}
val, err := Literal(cfg, idx.(*syntax.Word))
if err != nil {
return "", err
}
return vr.Map[val], nil
}
return "", nil
}
func (cfg *Config) namesByPrefix(prefix string) []string {
var names []string
cfg.Env.Each(func(name string, vr Variable) bool {
if strings.HasPrefix(name, prefix) {
names = append(names, name)
}
return true
})
return names
}