From 073728e7500d235860b1b547b73b96493d51c49e Mon Sep 17 00:00:00 2001
From: NunoSempere <nuno.semperelh@protonmail.com>
Date: Sat, 11 May 2024 11:08:03 +0100
Subject: [PATCH] rationalize parser

---
 f.go | 138 ++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 85 insertions(+), 53 deletions(-)

diff --git a/f.go b/f.go
index 645208d..a0943c3 100644
--- a/f.go
+++ b/f.go
@@ -41,8 +41,6 @@ func combineBounds(old_low, old_high, new_low, new_high float64) (float64, float
 }
 
 func main() {
-	var old_low, old_high float64
-
 	reader := bufio.NewReader(os.Stdin)
 	input, _ := reader.ReadString('\n')
 	input = strings.TrimSpace(input)
@@ -58,80 +56,114 @@ func main() {
 		fmt.Println(error_msg_start)
 		return
 	}
-
 	fmt.Printf("=> %.1f %.1f\n", old_low, old_high)
 
-	error_msg_cont := "Please enter two floats separated by a space, like: 1 10, or two floats preceded by a division, like: / 2 20. Or enter i to get the logmean and logstd"
+	error_msg_cont := "Valid inputs: 2 || * 2 || / 2 || 2 20 || * 2 20 || / 2 20 || i || e"
 EventForLoop:
 	for {
-		var new_low, new_high float64
-		var err1, err2 error
 		input, _ = reader.ReadString('\n')
 		if strings.TrimSpace(input) == "" {
 			continue EventForLoop
 		}
 		tokens := strings.Split(strings.TrimSpace(input), " ")
 
-		switch len(tokens) {
-		case 0:
-			continue EventForLoop
-		case 1:
-			single_float, err1 := strconv.ParseFloat(tokens[0], 64)
-			switch {
-			case tokens[0] == "i":
-				fmt.Printf("=> %.1f %.1f\n", old_low, old_high)
-				logmean_old, logstd_old := boundsToLogParams(old_low, old_high)
-				fmt.Printf("=> Lognormal, with logmean: %.1f, logstd: %.1f\n", logmean_old, logstd_old)
-				continue EventForLoop
-			case err1 != nil:
-				new_low = single_float
-				new_high = single_float
-			default:
+		var new_low, new_high float64
+		var err1, err2 error
+		err1, err2 = nil, nil
+
+		switch tokens[0] {
+		case "*":
+			switch len(tokens) {
+			case 1:
+				fmt.Println("Can't multiply by nothing")
 				fmt.Println(error_msg_cont)
 				continue EventForLoop
-			}
-		case 2:
-			new_low, err1 = strconv.ParseFloat(tokens[0], 64)
-			new_high, err2 = strconv.ParseFloat(tokens[1], 64)
-			if err2 != nil {
-				fmt.Println(error_msg_cont)
-				continue EventForLoop
-			}
-			switch tokens[0] {
-			case "*":
-				new_low = new_high
-			case "/":
-				new_low = 1.0 / new_high
-				new_high = new_low
-			default:
+			case 2:
+				single_float, err1 := strconv.ParseFloat(tokens[1], 64)
 				if err1 != nil {
+					fmt.Println("Trying to multiply by a scalar, but scalar is not a float")
 					fmt.Println(error_msg_cont)
 					continue EventForLoop
 				}
-			}
-		case 3:
-			new_low, err1 = strconv.ParseFloat(tokens[1], 64)
-			new_high, err2 = strconv.ParseFloat(tokens[2], 64)
-			if err1 != nil || err2 != nil {
-				fmt.Println(error_msg_cont)
-				continue EventForLoop
-			}
-			switch tokens[0] {
-			case "*":
-			case "/":
-				tmp_low := new_low
-				new_low = 1.0 / new_high
-				new_high = 1.0 / tmp_low
+				new_low = single_float
+				new_high = single_float
+			case 3:
+				new_low, err1 = strconv.ParseFloat(tokens[1], 64)
+				new_high, err2 = strconv.ParseFloat(tokens[2], 64)
+				if err1 != nil || err2 != nil {
+					fmt.Println(error_msg_cont)
+					fmt.Println("Trying to multiply by a distribution, but distribution is not specified as two floats")
+					continue EventForLoop
+				}
 			default:
+				fmt.Println("Trying to multiply by something, but this something is neither a scalar nor a distribution")
 				fmt.Println(error_msg_cont)
 				continue EventForLoop
 			}
+		case "/":
+			switch len(tokens) {
+			case 1:
+				fmt.Println("Can't divide by nothing")
+				fmt.Println(error_msg_cont)
+				continue EventForLoop
+			case 2:
+				single_float, err1 := strconv.ParseFloat(tokens[0], 64)
+				if err1 != nil {
+					fmt.Println("Trying to divide by a scalar, but scalar is not a float")
+					fmt.Println(error_msg_cont)
+					continue EventForLoop
+				}
+				new_low = 1.0 / single_float
+				new_high = 1.0 / single_float
+			case 3:
+				new_low, err1 = strconv.ParseFloat(tokens[1], 64)
+				new_high, err2 = strconv.ParseFloat(tokens[2], 64)
+				if err1 != nil || err2 != nil {
+					fmt.Println("Trying to divide by a distribution, but distribution is not specified as two floats")
+					fmt.Println(error_msg_cont)
+					continue EventForLoop
+				}
+			default:
+				fmt.Println("Trying to divide by something, but this something is neither a scalar nor a distribution")
+			}
 		default:
-			fmt.Println(error_msg_cont)
-			continue EventForLoop
+			switch len(tokens) {
+			case 0:
+				continue EventForLoop
+			case 1:
+				switch tokens[0] {
+				case "i":
+					fmt.Printf("=> %.1f %.1f\n", old_low, old_high)
+					logmean_old, logstd_old := boundsToLogParams(old_low, old_high)
+					fmt.Printf("=> Lognormal, with logmean: %.1f, logstd: %.1f\n", logmean_old, logstd_old)
+					continue EventForLoop
+				case "e":
+					break EventForLoop
+				default:
+					single_float, err1 := strconv.ParseFloat(tokens[0], 64)
+					if err1 != nil {
+						fmt.Println("Trying to multiply by a scalar, but scalar is not a float")
+						fmt.Println(error_msg_cont)
+						continue EventForLoop
+					}
+					new_low = single_float
+					new_high = single_float
+				}
+			case 2:
+				new_low, err1 = strconv.ParseFloat(tokens[0], 64)
+				new_high, err2 = strconv.ParseFloat(tokens[1], 64)
+				if err1 != nil || err2 != nil {
+					fmt.Println("Trying to multiply by a distribution, but distribution is not specified as two floats")
+					fmt.Println(error_msg_cont)
+					continue EventForLoop
+				}
+			default:
+				fmt.Println("No operation takes more than 3 words")
+				fmt.Println(error_msg_cont)
+				continue EventForLoop
+			}
 		}
 
-		// Use the abstracted function for combining floats
 		old_low, old_high = combineBounds(old_low, old_high, new_low, new_high)
 		fmt.Printf("=> %.1f %.1f\n", old_low, old_high)
 	}