adding truncate function support

Author: mschuchard

CHANGELOG.md

@@ -1,3 +1,6 @@
+### 2.3.0 (Next)
+- Add `truncate` function.
+
 ### 2.2.2
 - Update `exp`, `mod`, and `sqrt` functions' input parameter type from `float64` to `number`.
 - Update `sqrt` return type to `number`.

docs/index.md

@@ -48,6 +48,7 @@ The documentation overview for custom functions (available for Terraform version
 - [mod](functions/mod.html)
 - [round](functions/round.html)
 - [sqrt](functions/sqrt.html)
+- [truncate](functions/truncate.html)
 
 ### Map
 - [coalesce_map](functions/coalesce_map.html)

examples/functions/round/function.tf

@@ -1,11 +1,11 @@
-# Return the rounding of of 1.2:
+# Return the rounding of 1.2:
 provider::stdlib::round(1.2)
 # result => 1
 
-# Return the rounding of of 1.8:
+# Return the rounding of 1.8:
 provider::stdlib::round(1.8)
 # result => 2
 
-# Return the rounding of of 1.5:
+# Return the rounding of 1.5:
 provider::stdlib::round(1.5)
 # result => 2

examples/functions/truncate/function.tf

@@ -0,0 +1,7 @@
+# Return the truncation of 1.2345:
+provider::stdlib::truncate(1.2345)
+# result => 1
+
+# Return the truncation of -67.89:
+provider::stdlib::truncate(-67.89)
+# result => -67

stdlib/number/truncate_test.go

@@ -0,0 +1,57 @@
+package numberfunc_test
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-framework/attr"
+	"github.com/hashicorp/terraform-plugin-framework/function"
+	"github.com/hashicorp/terraform-plugin-framework/types"
+
+	util "github.com/mschuchard/terraform-provider-stdlib/internal"
+	numberfunc "github.com/mschuchard/terraform-provider-stdlib/stdlib/number"
+)
+
+func TestTruncateFunction(test *testing.T) {
+	// initialize initial result data
+	resultData := function.NewResultData(types.Int64Unknown())
+
+	testCases := util.TestCases{
+		"truncate-one": {
+			Request: function.RunRequest{
+				Arguments: function.NewArgumentsData([]attr.Value{types.Float64Value(1.2345)}),
+			},
+			Expected: function.RunResponse{
+				Result: function.NewResultData(types.Int64Value(1)),
+			},
+		},
+		"truncate-negative-sixty-seven": {
+			Request: function.RunRequest{
+				Arguments: function.NewArgumentsData([]attr.Value{types.Float64Value(-67.89)}),
+			},
+			Expected: function.RunResponse{
+				Result: function.NewResultData(types.Int64Value(-67)),
+			},
+		},
+		"beyond-upper-limit": {
+			Request: function.RunRequest{
+				Arguments: function.NewArgumentsData([]attr.Value{types.NumberValue(func() *big.Float { f := new(big.Float); f.SetString("1e+310"); return f }())}),
+			},
+			Expected: function.RunResponse{
+				Result: resultData,
+				Error:  function.NewArgumentFuncError(0, "truncate: input number is beyond the limits of float64"),
+			},
+		},
+		"overflow": {
+			Request: function.RunRequest{
+				Arguments: function.NewArgumentsData([]attr.Value{types.Float64Value(9.223372036854777e+18)}), // math.MaxInt64 + 1
+			},
+			Expected: function.RunResponse{
+				Result: resultData,
+				Error:  function.NewArgumentFuncError(0, "truncate: truncated input number is beyond the limits of int64"),
+			},
+		},
+	}
+
+	util.UnitTests(testCases, resultData, numberfunc.NewTruncateFunction(), test)
+}

stdlib/provider.go

@@ -102,6 +102,7 @@ func (*stdlibProvider) Functions(_ context.Context) []func() function.Function {
 		numberfunc.NewModFunction,
 		numberfunc.NewRoundFunction,
 		numberfunc.NewSqrtFunction,
+		numberfunc.NewTruncateFunction,
 		slicefunc.NewCompareListFunction,
 		slicefunc.NewElementsDeleteFunction,
 		slicefunc.NewInsertFunction,