Add coalesce func

This commit is contained in:
Matt Morrison 2015-11-08 19:34:56 +13:00
parent dc96d7e61b
commit 6ecec7fe83
3 changed files with 55 additions and 0 deletions

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@ -25,6 +25,7 @@ func init() {
"cidrhost": interpolationFuncCidrHost(),
"cidrnetmask": interpolationFuncCidrNetmask(),
"cidrsubnet": interpolationFuncCidrSubnet(),
"coalesce": interpolationFuncCoalesce(),
"compact": interpolationFuncCompact(),
"concat": interpolationFuncConcat(),
"element": interpolationFuncElement(),
@ -145,6 +146,30 @@ func interpolationFuncCidrSubnet() ast.Function {
}
}
// interpolationFuncCoalesce implements the "coalesce" function that
// returns the first non null / empty string from the provided input
func interpolationFuncCoalesce() ast.Function {
return ast.Function{
ArgTypes: []ast.Type{ast.TypeString},
ReturnType: ast.TypeString,
Variadic: true,
VariadicType: ast.TypeString,
Callback: func(args []interface{}) (interface{}, error) {
if len(args) < 2 {
return nil, fmt.Errorf("must provide at least two arguments")
}
for _, arg := range args {
argument := arg.(string)
if argument != "" {
return argument, nil
}
}
return "", nil
},
}
}
// 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

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@ -147,6 +147,33 @@ func TestInterpolateFuncCidrSubnet(t *testing.T) {
})
}
func TestInterpolateFuncCoalesce(t *testing.T) {
testFunction(t, testFunctionConfig{
Cases: []testFunctionCase{
{
`${coalesce("first", "second", "third")}`,
"first",
false,
},
{
`${coalesce("", "second", "third")}`,
"second",
false,
},
{
`${coalesce("", "", "")}`,
"",
false,
},
{
`${coalesce("foo")}`,
nil,
true,
},
},
})
}
func TestInterpolateFuncDeprecatedConcat(t *testing.T) {
testFunction(t, testFunctionConfig{
Cases: []testFunctionCase{

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@ -96,6 +96,9 @@ The supported built-in functions are:
additional subnet number. For example,
``cidrsubnet("10.0.0.0/8", 8, 2)`` returns ``10.2.0.0/16``.
* `coalesce(string1, string2, ...)` - Returns the first non-empty value from
the given arguments. At least two arguments must be provided.
* `compact(list)` - Removes empty string elements from a list. This can be
useful in some cases, for example when passing joined lists as module
variables or when parsing module outputs.