add prototype of modulus function

stdlib/number/mod.go

@@ -0,0 +1,69 @@
+package numberfunc
+
+import (
+	"context"
+	"math"
+
+	"github.com/hashicorp/terraform-plugin-framework/function"
+	"github.com/hashicorp/terraform-plugin-log/tflog"
+)
+
+// ensure the implementation satisfies the expected interfaces
+var _ function.Function = &modFunction{}
+
+// helper pseudo-constructor to simplify provider server and testing implementation
+func NewModFunction() function.Function {
+	return &modFunction{}
+}
+
+// function implementation
+type modFunction struct{}
+
+// function metadata
+func (*modFunction) Metadata(_ context.Context, req function.MetadataRequest, resp *function.MetadataResponse) {
+	resp.Name = "mod"
+}
+
+// define the provider-level definition for the function
+func (*modFunction) Definition(_ context.Context, _ function.DefinitionRequest, resp *function.DefinitionResponse) {
+	resp.Definition = function.Definition{
+		Summary:             "Determine modulus of a number",
+		MarkdownDescription: "Return the remainder of the dividend number divided by the divisor number.",
+		Parameters: []function.Parameter{
+			function.Float64Parameter{
+				Name:        "dividend",
+				Description: "The dividend number from which to divide.",
+			},
+			function.Float64Parameter{
+				Name:        "divisor",
+				Description: "The divisor number by which to divide.",
+			},
+		},
+		Return: function.Float64Return{},
+	}
+}
+
+func (*modFunction) Run(ctx context.Context, req function.RunRequest, resp *function.RunResponse) {
+	// initialize input parameters
+	var dividend, divisor float64
+
+	resp.Error = function.ConcatFuncErrors(resp.Error, req.Arguments.Get(ctx, &dividend, &divisor))
+	if resp.Error != nil {
+		return
+	}
+
+	ctx = tflog.SetField(ctx, "mod: dividend", dividend)
+	ctx = tflog.SetField(ctx, "mod: divisor", divisor)
+
+	// determine the modulus
+	modulus := math.Mod(dividend, divisor)
+	ctx = tflog.SetField(ctx, "mod: modulus", modulus)
+
+	// store the result as a float64
+	resp.Error = function.ConcatFuncErrors(resp.Error, resp.Result.Set(ctx, &modulus))
+	if resp.Error != nil {
+		return
+	}
+
+	tflog.Debug(ctx, "mod: successful return", map[string]any{"success": true})
+}