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package hclwrite
import (
"fmt"
"unicode"
"unicode/utf8"
"github.com/hashicorp/hcl2/hcl"
"github.com/hashicorp/hcl2/hcl/hclsyntax"
"github.com/zclconf/go-cty/cty"
)
// TokensForValue returns a sequence of tokens that represents the given
// constant value.
//
// This function only supports types that are used by HCL. In particular, it
// does not support capsule types and will panic if given one.
//
// It is not possible to express an unknown value in source code, so this
// function will panic if the given value is unknown or contains any unknown
// values. A caller can call the value's IsWhollyKnown method to verify that
// no unknown values are present before calling TokensForValue.
func TokensForValue(val cty.Value) Tokens {
toks := appendTokensForValue(val, nil)
format(toks) // fiddle with the SpacesBefore field to get canonical spacing
return toks
}
// TokensForTraversal returns a sequence of tokens that represents the given
// traversal.
//
// If the traversal is absolute then the result is a self-contained, valid
// reference expression. If the traversal is relative then the returned tokens
// could be appended to some other expression tokens to traverse into the
// represented expression.
func TokensForTraversal(traversal hcl.Traversal) Tokens {
toks := appendTokensForTraversal(traversal, nil)
format(toks) // fiddle with the SpacesBefore field to get canonical spacing
return toks
}
func appendTokensForValue(val cty.Value, toks Tokens) Tokens {
switch {
case !val.IsKnown():
panic("cannot produce tokens for unknown value")
case val.IsNull():
toks = append(toks, &Token{
Type: hclsyntax.TokenIdent,
Bytes: []byte(`null`),
})
case val.Type() == cty.Bool:
var src []byte
if val.True() {
src = []byte(`true`)
} else {
src = []byte(`false`)
}
toks = append(toks, &Token{
Type: hclsyntax.TokenIdent,
Bytes: src,
})
case val.Type() == cty.Number:
bf := val.AsBigFloat()
srcStr := bf.Text('f', -1)
toks = append(toks, &Token{
Type: hclsyntax.TokenNumberLit,
Bytes: []byte(srcStr),
})
case val.Type() == cty.String:
// TODO: If it's a multi-line string ending in a newline, format
// it as a HEREDOC instead.
src := escapeQuotedStringLit(val.AsString())
toks = append(toks, &Token{
Type: hclsyntax.TokenOQuote,
Bytes: []byte{'"'},
})
if len(src) > 0 {
toks = append(toks, &Token{
Type: hclsyntax.TokenQuotedLit,
Bytes: src,
})
}
toks = append(toks, &Token{
Type: hclsyntax.TokenCQuote,
Bytes: []byte{'"'},
})
case val.Type().IsListType() || val.Type().IsSetType() || val.Type().IsTupleType():
toks = append(toks, &Token{
Type: hclsyntax.TokenOBrack,
Bytes: []byte{'['},
})
i := 0
for it := val.ElementIterator(); it.Next(); {
if i > 0 {
toks = append(toks, &Token{
Type: hclsyntax.TokenComma,
Bytes: []byte{','},
})
}
_, eVal := it.Element()
toks = appendTokensForValue(eVal, toks)
i++
}
toks = append(toks, &Token{
Type: hclsyntax.TokenCBrack,
Bytes: []byte{']'},
})
case val.Type().IsMapType() || val.Type().IsObjectType():
toks = append(toks, &Token{
Type: hclsyntax.TokenOBrace,
Bytes: []byte{'{'},
})
i := 0
for it := val.ElementIterator(); it.Next(); {
if i > 0 {
toks = append(toks, &Token{
Type: hclsyntax.TokenComma,
Bytes: []byte{','},
})
}
eKey, eVal := it.Element()
if hclsyntax.ValidIdentifier(eKey.AsString()) {
toks = append(toks, &Token{
Type: hclsyntax.TokenIdent,
Bytes: []byte(eKey.AsString()),
})
} else {
toks = appendTokensForValue(eKey, toks)
}
toks = append(toks, &Token{
Type: hclsyntax.TokenEqual,
Bytes: []byte{'='},
})
toks = appendTokensForValue(eVal, toks)
i++
}
toks = append(toks, &Token{
Type: hclsyntax.TokenCBrace,
Bytes: []byte{'}'},
})
default:
panic(fmt.Sprintf("cannot produce tokens for %#v", val))
}
return toks
}
func appendTokensForTraversal(traversal hcl.Traversal, toks Tokens) Tokens {
for _, step := range traversal {
appendTokensForTraversalStep(step, toks)
}
return toks
}
func appendTokensForTraversalStep(step hcl.Traverser, toks Tokens) {
switch ts := step.(type) {
case hcl.TraverseRoot:
toks = append(toks, &Token{
Type: hclsyntax.TokenIdent,
Bytes: []byte(ts.Name),
})
case hcl.TraverseAttr:
toks = append(
toks,
&Token{
Type: hclsyntax.TokenDot,
Bytes: []byte{'.'},
},
&Token{
Type: hclsyntax.TokenIdent,
Bytes: []byte(ts.Name),
},
)
case hcl.TraverseIndex:
toks = append(toks, &Token{
Type: hclsyntax.TokenOBrack,
Bytes: []byte{'['},
})
appendTokensForValue(ts.Key, toks)
toks = append(toks, &Token{
Type: hclsyntax.TokenCBrack,
Bytes: []byte{']'},
})
default:
panic(fmt.Sprintf("unsupported traversal step type %T", step))
}
}
func escapeQuotedStringLit(s string) []byte {
if len(s) == 0 {
return nil
}
buf := make([]byte, 0, len(s))
for i, r := range s {
switch r {
case '\n':
buf = append(buf, '\\', 'n')
case '\r':
buf = append(buf, '\\', 'r')
case '\t':
buf = append(buf, '\\', 't')
case '"':
buf = append(buf, '\\', '"')
case '\\':
buf = append(buf, '\\', '\\')
case '$', '%':
buf = appendRune(buf, r)
remain := s[i+1:]
if len(remain) > 0 && remain[0] == '{' {
// Double up our template introducer symbol to escape it.
buf = appendRune(buf, r)
}
default:
if !unicode.IsPrint(r) {
var fmted string
if r < 65536 {
fmted = fmt.Sprintf("\\u%04x", r)
} else {
fmted = fmt.Sprintf("\\U%08x", r)
}
buf = append(buf, fmted...)
} else {
buf = appendRune(buf, r)
}
}
}
return buf
}
func appendRune(b []byte, r rune) []byte {
l := utf8.RuneLen(r)
for i := 0; i < l; i++ {
b = append(b, 0) // make room at the end of our buffer
}
ch := b[len(b)-l:]
utf8.EncodeRune(ch, r)
return b
}
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