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ParseFunction.go
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ParseFunction.go
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package main
import (
//"errors"
"github.com/Knetic/govaluate"
"log"
. "math"
"reflect"
"strconv"
"strings"
)
var functions map[string]govaluate.ExpressionFunction
func init() {
functions = make(map[string]govaluate.ExpressionFunction)
functions["strlen"] = func(args ...interface{}) (interface{}, error) {
length := len(args[0].(string))
return (float64)(length), nil
}
functions["sin"] = func(args ...interface{}) (interface{}, error) {
return Sin(args[0].(float64)), nil
}
functions["cos"] = func(args ...interface{}) (interface{}, error) {
return Cos(args[0].(float64)), nil
}
functions["pow"] = func(args ...interface{}) (interface{}, error) {
return Pow(args[0].(float64), args[1].(float64)), nil
}
functions["PI"] = func(args ...interface{}) (interface{}, error) {
return Pi, nil
}
}
/* statistics of functions:
n of iter: 314160
EvalWithParams2:
7534605279
EvalWithParams:
9022396575
ParseFunction:
6428727151
NewEval with const:
8585686337
Normal function:
45168146
*/
/// @funcStr is string. It may have maximum of three parameters. Parameters must be signed as "x", "y", "z"
/// @args - at least two arguments: 1.: channel; 2.: float64
/// example:
/// go ParseFunction(funcStr, channelString, i, i)
/// go EvaluateFunction(<-channelString, channelEval)
func ParseFunction(str string, args ...interface{}) {
if (reflect.TypeOf(args[0]).String()) != "chan string" {
log.Fatal("First argument must be a channel.")
return
}
if len(args) < 2 {
log.Fatal("You must have at least one channel and one value argument.")
return
}
if len(args) > 4 {
log.Fatal("You can't have more than 3 value arguments.")
return
}
for i := 1; i < len(args); i++ {
if reflect.TypeOf(args[i]).String() != "float64" {
log.Fatal("Argument " + strconv.FormatInt(int64(i+1), 10) + " is not float64")
return
}
}
valMap := []string{"x", "y", "z"}
var result string
for i := 1; i < len(args); i++ {
value := args[i].(float64)
result = ""
sliceStr := strings.Split(str, valMap[i-1])
for j := 0; j < len(sliceStr); j++ {
result += sliceStr[j]
if j+1 < len(sliceStr) {
result += strconv.FormatFloat(value, 'f', -1, 64)
}
}
str = result
}
args[0].(chan string) <- result
return
}
func EvaluateFunction(str string, out chan float64) {
expression, _ := govaluate.NewEvaluableExpressionWithFunctions(str, functions)
val, _ := expression.Evaluate(nil)
out <- val.(float64)
}
/// args must be a pair of value name (string) and value (float64)
/// example:
/// go EvaluateWithParameters(funcStr, channelEval, "x", i, "y", i)
func EvaluateWithParameters(str string, out chan float64, args ...interface{}) {
pairLen := len(args) / 2
params := make(map[string]interface{}, pairLen)
for i := 0; i < pairLen*2; i += 2 {
params[args[i].(string)] = args[i+1].(float64)
}
expression, _ := govaluate.NewEvaluableExpressionWithFunctions(str, functions)
val, _ := expression.Evaluate(params)
out <- val.(float64)
}
/// example:
/// parameters := make(map[string]interface{}, 1)
/// parameters["x"] = i;
/// parameters["y"] = i;
/// go EvaluateWithParameters2(funcStr, parameters, channelEval)
/// go FlushChannel(channelEval)
func EvaluateWithParameters2(str string, params map[string]interface{}, out chan float64) {
expression, _ := govaluate.NewEvaluableExpressionWithFunctions(str, functions)
val, _ := expression.Evaluate(params)
out <- val.(float64)
}
func FlushChannel(c chan float64) {
<-c
}