forked from hashicorp/terraform
/
interpolate_funcs.go
280 lines (251 loc) · 7.77 KB
/
interpolate_funcs.go
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package config
import (
"bytes"
"errors"
"fmt"
"io/ioutil"
"regexp"
"strconv"
"strings"
"github.com/hashicorp/terraform/config/lang/ast"
"github.com/mitchellh/go-homedir"
)
// Funcs is the mapping of built-in functions for configuration.
var Funcs map[string]ast.Function
func init() {
Funcs = map[string]ast.Function{
"file": interpolationFuncFile(),
"format": interpolationFuncFormat(),
"formatlist": interpolationFuncFormatList(),
"join": interpolationFuncJoin(),
"element": interpolationFuncElement(),
"replace": interpolationFuncReplace(),
"split": interpolationFuncSplit(),
"length": interpolationFuncLength(),
// Concat is a little useless now since we supported embeddded
// interpolations but we keep it around for backwards compat reasons.
"concat": interpolationFuncConcat(),
}
}
// interpolationFuncConcat implements the "concat" function that
// concatenates multiple strings. This isn't actually necessary anymore
// since our language supports string concat natively, but for backwards
// compat we do this.
func interpolationFuncConcat() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString},
ReturnType: ast.TypeString,
Variadic: true,
VariadicType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
var b bytes.Buffer
for _, v := range args {
b.WriteString(v.(string))
}
return b.String(), nil
},
}
}
// interpolationFuncFile implements the "file" function that allows
// loading contents from a file.
func interpolationFuncFile() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString},
ReturnType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
path, err := homedir.Expand(args[0].(string))
if err != nil {
return "", err
}
data, err := ioutil.ReadFile(path)
if err != nil {
return "", err
}
return string(data), nil
},
}
}
// interpolationFuncFormat implements the "format" function that does
// string formatting.
func interpolationFuncFormat() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString},
Variadic: true,
VariadicType: ast.TypeAny,
ReturnType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
format := args[0].(string)
return fmt.Sprintf(format, args[1:]...), nil
},
}
}
// interpolationFuncFormatList implements the "formatlist" function that does
// string formatting on lists.
func interpolationFuncFormatList() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString},
Variadic: true,
VariadicType: ast.TypeAny,
ReturnType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
// Make a copy of the variadic part of args
// to avoid modifying the original.
varargs := make([]interface{}, len(args)-1)
copy(varargs, args[1:])
// Convert arguments that are lists into slices.
// Confirm along the way that all lists have the same length (n).
var n int
for i := 1; i < len(args); i++ {
s, ok := args[i].(string)
if !ok {
continue
}
parts := strings.Split(s, InterpSplitDelim)
if len(parts) == 1 {
continue
}
varargs[i-1] = parts
if n == 0 {
// first list we've seen
n = len(parts)
continue
}
if n != len(parts) {
return nil, fmt.Errorf("format: mismatched list lengths: %d != %d", n, len(parts))
}
}
if n == 0 {
return nil, errors.New("no lists in arguments to formatlist")
}
// Do the formatting.
format := args[0].(string)
// Generate a list of formatted strings.
list := make([]string, n)
fmtargs := make([]interface{}, len(varargs))
for i := 0; i < n; i++ {
for j, arg := range varargs {
switch arg := arg.(type) {
default:
fmtargs[j] = arg
case []string:
fmtargs[j] = arg[i]
}
}
list[i] = fmt.Sprintf(format, fmtargs...)
}
return strings.Join(list, InterpSplitDelim), nil
},
}
}
// interpolationFuncJoin implements the "join" function that allows
// multi-variable values to be joined by some character.
func interpolationFuncJoin() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString, ast.TypeString},
ReturnType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
var list []string
for _, arg := range args[1:] {
parts := strings.Split(arg.(string), InterpSplitDelim)
list = append(list, parts...)
}
return strings.Join(list, args[0].(string)), nil
},
}
}
// interpolationFuncReplace implements the "replace" function that does
// string replacement.
func interpolationFuncReplace() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString, ast.TypeString, ast.TypeString},
ReturnType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
s := args[0].(string)
search := args[1].(string)
replace := args[2].(string)
// We search/replace using a regexp if the string is surrounded
// in forward slashes.
if len(search) > 1 && search[0] == '/' && search[len(search)-1] == '/' {
re, err := regexp.Compile(search[1 : len(search)-1])
if err != nil {
return nil, err
}
return re.ReplaceAllString(s, replace), nil
}
return strings.Replace(s, search, replace, -1), nil
},
}
}
func interpolationFuncLength() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString},
ReturnType: ast.TypeInt,
Variadic: false,
Callback: func(args []interface{}) (interface{}, error) {
if !strings.Contains(args[0].(string), InterpSplitDelim) {
return len(args[0].(string)), nil
}
var list []string
for _, arg := range args {
parts := strings.Split(arg.(string), InterpSplitDelim)
for _, part := range parts {
list = append(list, part)
}
}
return len(list), nil
},
}
}
// interpolationFuncSplit implements the "split" function that allows
// strings to split into multi-variable values
func interpolationFuncSplit() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString, ast.TypeString},
ReturnType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
return strings.Replace(args[1].(string), args[0].(string), InterpSplitDelim, -1), nil
},
}
}
// interpolationFuncLookup implements the "lookup" function that allows
// dynamic lookups of map types within a Terraform configuration.
func interpolationFuncLookup(vs map[string]ast.Variable) ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString, ast.TypeString},
ReturnType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
k := fmt.Sprintf("var.%s.%s", args[0].(string), args[1].(string))
v, ok := vs[k]
if !ok {
return "", fmt.Errorf(
"lookup in '%s' failed to find '%s'",
args[0].(string), args[1].(string))
}
if v.Type != ast.TypeString {
return "", fmt.Errorf(
"lookup in '%s' for '%s' has bad type %s",
args[0].(string), args[1].(string), v.Type)
}
return v.Value.(string), nil
},
}
}
// interpolationFuncElement implements the "element" function that allows
// a specific index to be looked up in a multi-variable value. Note that this will
// wrap if the index is larger than the number of elements in the multi-variable value.
func interpolationFuncElement() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString, ast.TypeString},
ReturnType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
list := strings.Split(args[0].(string), InterpSplitDelim)
index, err := strconv.Atoi(args[1].(string))
if err != nil {
return "", fmt.Errorf(
"invalid number for index, got %s", args[1])
}
v := list[index%len(list)]
return v, nil
},
}
}