feat: add grammar and functions call support

pkg/grammar/functions.go

@@ -0,0 +1,50 @@
+package grammar
+
+import (
+	"encoding/json"
+)
+
+type Function struct {
+	Name        string                 `json:"name"`
+	Description string                 `json:"description"`
+	Parameters  map[string]interface{} `json:"parameters"`
+}
+type Functions []Function
+
+func (f Functions) ToJSONStructure() JSONStructure {
+	js := JSONStructure{}
+	for _, function := range f {
+		//	t := function.Parameters["type"]
+		//tt := t.(string)
+
+		properties := function.Parameters["properties"]
+		dat, _ := json.Marshal(properties)
+		prop := map[string]interface{}{}
+		json.Unmarshal(dat, &prop)
+		js.OneOf = append(js.OneOf, Item{
+			Type: "object",
+			Properties: Properties{
+				Function: FunctionName{Const: function.Name},
+				Arguments: Argument{
+					Type:       "object",
+					Properties: prop,
+				},
+			},
+		})
+	}
+	return js
+}
+
+// Select returns a list of functions containing the function with the given name
+func (f Functions) Select(name string) Functions {
+	var funcs Functions
+
+	for _, f := range f {
+		if f.Name == name {
+			funcs = []Function{f}
+			break
+		}
+	}
+
+	return funcs
+}