Merge pull request #554 from rcostanzo/f-array-index

Added an element interpolation lookup function for accessing a specific ...
This commit is contained in:
Armon Dadgar 2014-11-19 16:02:34 -08:00
commit 4cdeb4b846
3 changed files with 77 additions and 0 deletions

View File

@ -4,6 +4,7 @@ import (
"bytes" "bytes"
"fmt" "fmt"
"io/ioutil" "io/ioutil"
"strconv"
"strings" "strings"
) )
@ -16,6 +17,7 @@ func init() {
"file": interpolationFuncFile, "file": interpolationFuncFile,
"join": interpolationFuncJoin, "join": interpolationFuncJoin,
"lookup": interpolationFuncLookup, "lookup": interpolationFuncLookup,
"element": interpolationFuncElement,
} }
} }
@ -87,3 +89,26 @@ func interpolationFuncLookup(
return v, nil return v, 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(
vs map[string]string, args ...string) (string, error) {
if len(args) != 2 {
return "", fmt.Errorf(
"element expects 2 arguments, got %d", len(args))
}
list := strings.Split(args[0], InterpSplitDelim)
index, err := strconv.Atoi(args[1])
if err != nil {
return "", fmt.Errorf(
"invalid number for index, got %s", args[1])
}
v := list[index % len(list)]
return v, nil
}

View File

@ -189,3 +189,48 @@ func TestInterpolateFuncLookup(t *testing.T) {
} }
} }
} }
func TestInterpolateFuncElement(t *testing.T) {
cases := []struct {
Args []string
Result string
Error bool
}{
{
[]string{"foo" + InterpSplitDelim + "baz", "1"},
"baz",
false,
},
{
[]string{"foo", "0"},
"foo",
false,
},
// Invalid index should wrap vs. out-of-bounds
{
[]string{"foo" + InterpSplitDelim + "baz", "2"},
"foo",
false,
},
// Too many args
{
[]string{"foo" + InterpSplitDelim + "baz", "0", "1"},
"",
true,
},
}
for i, tc := range cases {
actual, err := interpolationFuncElement(nil, tc.Args...)
if (err != nil) != tc.Error {
t.Fatalf("%d: err: %s", i, err)
}
if actual != tc.Result {
t.Fatalf("%d: bad: %#v", i, actual)
}
}
}

View File

@ -74,3 +74,10 @@ The supported built-in functions are:
* `lookup(map, key)` - Performs a dynamic lookup into a mapping * `lookup(map, key)` - Performs a dynamic lookup into a mapping
variable. variable.
* `element(list, index)` - Returns a single element from a list
at the given index. If the index is greater than the number of
elements, this function will wrap using a standard mod algorithm.
A list is only possible with splat variables from resources with
a count greater than one.
Example: `element(aws_subnet.foo.*.id, count.index)`