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package stdlib
import (
"strings"
"github.com/zclconf/go-cty/cty"
"github.com/zclconf/go-cty/cty/function"
"github.com/zclconf/go-cty/cty/gocty"
"github.com/apparentlymart/go-textseg/textseg"
)
var UpperFunc = function.New(&function.Spec{
Params: []function.Parameter{
{
Name: "str",
Type: cty.String,
AllowDynamicType: true,
},
},
Type: function.StaticReturnType(cty.String),
Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
in := args[0].AsString()
out := strings.ToUpper(in)
return cty.StringVal(out), nil
},
})
var LowerFunc = function.New(&function.Spec{
Params: []function.Parameter{
{
Name: "str",
Type: cty.String,
AllowDynamicType: true,
},
},
Type: function.StaticReturnType(cty.String),
Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
in := args[0].AsString()
out := strings.ToLower(in)
return cty.StringVal(out), nil
},
})
var ReverseFunc = function.New(&function.Spec{
Params: []function.Parameter{
{
Name: "str",
Type: cty.String,
AllowDynamicType: true,
},
},
Type: function.StaticReturnType(cty.String),
Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
in := []byte(args[0].AsString())
out := make([]byte, len(in))
pos := len(out)
inB := []byte(in)
for i := 0; i < len(in); {
d, _, _ := textseg.ScanGraphemeClusters(inB[i:], true)
cluster := in[i : i+d]
pos -= len(cluster)
copy(out[pos:], cluster)
i += d
}
return cty.StringVal(string(out)), nil
},
})
var StrlenFunc = function.New(&function.Spec{
Params: []function.Parameter{
{
Name: "str",
Type: cty.String,
AllowDynamicType: true,
},
},
Type: function.StaticReturnType(cty.Number),
Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
in := args[0].AsString()
l := 0
inB := []byte(in)
for i := 0; i < len(in); {
d, _, _ := textseg.ScanGraphemeClusters(inB[i:], true)
l++
i += d
}
return cty.NumberIntVal(int64(l)), nil
},
})
var SubstrFunc = function.New(&function.Spec{
Params: []function.Parameter{
{
Name: "str",
Type: cty.String,
AllowDynamicType: true,
},
{
Name: "offset",
Type: cty.Number,
AllowDynamicType: true,
},
{
Name: "length",
Type: cty.Number,
AllowDynamicType: true,
},
},
Type: function.StaticReturnType(cty.String),
Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
in := []byte(args[0].AsString())
var offset, length int
var err error
err = gocty.FromCtyValue(args[1], &offset)
if err != nil {
return cty.NilVal, err
}
err = gocty.FromCtyValue(args[2], &length)
if err != nil {
return cty.NilVal, err
}
if offset < 0 {
totalLenNum, err := Strlen(args[0])
if err != nil {
// should never happen
panic("Stdlen returned an error")
}
var totalLen int
err = gocty.FromCtyValue(totalLenNum, &totalLen)
if err != nil {
// should never happen
panic("Stdlen returned a non-int number")
}
offset += totalLen
}
sub := in
pos := 0
var i int
// First we'll seek forward to our offset
if offset > 0 {
for i = 0; i < len(sub); {
d, _, _ := textseg.ScanGraphemeClusters(sub[i:], true)
i += d
pos++
if pos == offset {
break
}
if i >= len(in) {
return cty.StringVal(""), nil
}
}
sub = sub[i:]
}
if length < 0 {
// Taking the remainder of the string is a fast path since
// we can just return the rest of the buffer verbatim.
return cty.StringVal(string(sub)), nil
}
// Otherwise we need to start seeking forward again until we
// reach the length we want.
pos = 0
for i = 0; i < len(sub); {
d, _, _ := textseg.ScanGraphemeClusters(sub[i:], true)
i += d
pos++
if pos == length {
break
}
}
sub = sub[:i]
return cty.StringVal(string(sub)), nil
},
})
// Upper is a Function that converts a given string to uppercase.
func Upper(str cty.Value) (cty.Value, error) {
return UpperFunc.Call([]cty.Value{str})
}
// Lower is a Function that converts a given string to lowercase.
func Lower(str cty.Value) (cty.Value, error) {
return LowerFunc.Call([]cty.Value{str})
}
// Reverse is a Function that reverses the order of the characters in the
// given string.
//
// As usual, "character" for the sake of this function is a grapheme cluster,
// so combining diacritics (for example) will be considered together as a
// single character.
func Reverse(str cty.Value) (cty.Value, error) {
return ReverseFunc.Call([]cty.Value{str})
}
// Strlen is a Function that returns the length of the given string in
// characters.
//
// As usual, "character" for the sake of this function is a grapheme cluster,
// so combining diacritics (for example) will be considered together as a
// single character.
func Strlen(str cty.Value) (cty.Value, error) {
return StrlenFunc.Call([]cty.Value{str})
}
// Substr is a Function that extracts a sequence of characters from another
// string and creates a new string.
//
// As usual, "character" for the sake of this function is a grapheme cluster,
// so combining diacritics (for example) will be considered together as a
// single character.
//
// The "offset" index may be negative, in which case it is relative to the
// end of the given string.
//
// The "length" may be -1, in which case the remainder of the string after
// the given offset will be returned.
func Substr(str cty.Value, offset cty.Value, length cty.Value) (cty.Value, error) {
return SubstrFunc.Call([]cty.Value{str, offset, length})
}
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