parser fun

gistfile1.go

package main

import "fmt"
import "go/parser"
import "go/ast"

const debug = true

// Define one of these for each translation you need.
type Translator func(node *ast.CallExpr) string

// Should be loaded from the database or csv file...
var Database = map[string]string{
	"SwitchOnLight":  "buildRfidCmd(MAIN,Frame1,CL=clear,RW=WRITE);\nbuildRfidCmd(MAIN,Frame2,TIME1=%[1]sus,TIME2=%[1]sus,TIME3=%[2]sus,TIME4=0ms,RW=WRITE);",
	"SwitchOffLight": "buildRfidCmd(MAIN,Frame1,CL=clear,RW=WRITE);",
}

// Represents a basic identifier such as int_lit | float_lit | imaginary_lit | rune_lit | string_lit
func isBasicLit(node *ast.CallExpr) bool {
	for i, _ := range node.Args {
		_, ok := node.Args[i].(*ast.BasicLit)

		if !ok {
			return false
		}
	}

	return true
}

// Represents an identifier
func isIdent(name *ast.Expr) bool {
	if _, ok := (*name).(*ast.Ident); ok {
		return true
	}

	return false
}

// Map from input language to translators
var mapping = map[string]Translator{
	"SwitchOnLight": func(node *ast.CallExpr) string {
		var out string

		// Check this type assertion first
		if isBasicLit(node) {
			value1 := node.Args[0].(*ast.BasicLit).Value
			value2 := node.Args[1].(*ast.BasicLit).Value
			out = fmt.Sprintf(Database["SwitchOnLight"], value1, value2)
		}

		return out
	},
	"SwitchOffLight": func(node *ast.CallExpr) string {
		out := fmt.Sprintf(Database["SwitchOffLight"])
		return out
	},
}

func main() {
	fileContent := []string{"SwitchOnLight(700, 200);", "SwitchOffLight();"}

	for _, line := range fileContent {
		expr, err := parser.ParseExpr(line)
		if err != nil {
			fmt.Println(err.Error)
			return
		}

		if debug {
			fmt.Println("\n",expr)
			fmt.Printf("Expression Type: %T\n\n", expr)
		}
		
		if call, ok := expr.(*ast.CallExpr); ok {
			if debug {
					       fmt.Println("Function Call:")
			       fmt.Println("Function:", call.Fun)
			}

			// Check to make sure it's an *ast.Ident, so you don't get a panic here
			if isIdent(&call.Fun) {
				translator, ok := mapping[call.Fun.(*ast.Ident).Name]
				if ok {
					fmt.Println("Result:\n", translator(call))
				}
			}

		}
	}
}