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package main
import (
"fmt"
"os"
"strings"
"codeberg.org/snonux/perc/internal"
"codeberg.org/snonux/perc/internal/calculator"
"codeberg.org/snonux/perc/internal/rpn"
"codeberg.org/snonux/perc/internal/repl"
"github.com/mattn/go-isatty"
)
func main() {
output, err := runCommand(os.Args)
if err != nil {
fmt.Println("Error:", err)
os.Exit(1)
}
fmt.Println(output)
}
func runCommand(args []string) (string, error) {
if len(args) < 2 {
// No args provided - check if stdin is a TTY for REPL mode
if isatty.IsTerminal(os.Stdin.Fd()) {
repl.RunREPL()
return "", nil
}
printUsage()
return "", fmt.Errorf("no input provided")
}
if args[1] == "version" {
return internal.Version, nil
}
// Check for --repl flag
if args[1] == "--repl" || args[1] == "repl" {
repl.RunREPL()
return "", nil
}
// Check for calc subcommand
if args[1] == "calc" || args[1] == "rpn" {
if len(args) < 3 {
return "", fmt.Errorf("missing expression after '%s'", args[1])
}
input := strings.Join(args[2:], " ")
result, err := runRPN(input)
if err != nil {
return "", err
}
return result, nil
}
input := strings.Join(args[1:], " ")
// Try RPN parsing first (for bare RPN expressions like "3 4 +")
if rpnResult, rpnErr := runRPN(input); rpnErr == nil {
return rpnResult, nil
}
// Fall back to percentage calculation
result, err := calculator.Parse(input)
if err != nil {
return "", err
}
return result, nil
}
// runRPN parses and evaluates an RPN expression
func runRPN(input string) (string, error) {
vars := rpn.NewVariables()
rpnCalc := rpn.NewRPN(vars)
return rpnCalc.ParseAndEvaluate(input)
}
func printUsage() {
fmt.Println("Usage: perc <calculation>")
fmt.Println(" perc calc <rpn-expression>")
fmt.Println(" perc rpn <rpn-expression>")
fmt.Println(" perc version")
fmt.Println(" perc [--repl|repl]")
fmt.Println("\nPercentage calculator examples:")
fmt.Println(" perc 20% of 150")
fmt.Println(" perc what is 20% of 150")
fmt.Println(" perc 30 is what % of 150")
fmt.Println(" perc 30 is 20% of what")
fmt.Println("\nRPN (postfix notation) examples:")
fmt.Println(" perc calc 3 4 +")
fmt.Println(" perc calc 3 4 + 4 4 - *")
fmt.Println(" perc calc x = 5 x x +")
fmt.Println(" perc calc 2 3 ^")
fmt.Println(" perc calc dup swap pop show")
fmt.Println("\nStart REPL mode interactively by running without arguments:")
fmt.Println(" perc")
}
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