feat: detect CSV delimiter

Implements #20

/spend 5d

README.md

@@ -18,10 +18,10 @@ Hand-made builds are provided in the [Assets of each Release](https://github.com
 
 Say you have a tally CSV like so:
 
-	     , reject, poor, fair, good, very good, excellent
-	Pizza,      3,    2,    1,    4,         4,        2
-	Chips,      2,    3,    0,    4,         3,        4
-	Pasta,      4,    5,    1,    4,         0,        2
+         , reject, poor, fair, good, very good, excellent
+    Pizza,      3,    2,    1,    4,         4,        2
+    Chips,      2,    3,    0,    4,         3,        4
+    Pasta,      4,    5,    1,    4,         0,        2
 
 You can run
 

example/example.csv

@@ -1,4 +1,4 @@
-	     , reject, poor, fair, good, very good, excellent
-	Pizza,      3,    2,    1,    4,         4,        2
-	Chips,      2,    3,    0,    4,         3,        4
-	Pasta,      4,    5,    1,    4,         0,        2
+         , reject, poor, fair, good, very good, excellent
+    Pizza,      3,    2,    1,    4,         4,        2
+    Chips,      2,    3,    0,    4,         3,        4
+    Pasta,      4,    5,    1,    4,         0,        2

example/example10.tsv

@@ -0,0 +1,3 @@
+Pizza	3	2	1	4	4	2
+Chips	2	3	0	4	3	4
+Pasta	4	5	1	4	0	2

go.mod

@@ -3,6 +3,7 @@ module github.com/MieuxVoter/majority-judgment-cli
 go 1.17
 
 require (
+	github.com/csimplestring/go-csv v0.0.0-20180328183906-5b8b3cd94f2c
 	github.com/mieuxvoter/majority-judgment-library-go v0.3.1
 	github.com/spf13/cobra v1.2.1
 	github.com/spf13/viper v1.9.0

reader/csv_tally.go

@@ -3,6 +3,8 @@ package reader
 import (
 	"encoding/csv"
 	"errors"
+	"fmt"
+	"github.com/csimplestring/go-csv/detector"
 	"io"
 	"strings"
 )
@@ -16,9 +18,29 @@ func (r CsvTallyReader) Read(input *io.Reader) (
 	grades []string,
 	err error,
 ) {
+	csvDelimiter := ',' // default value if our detector below fails
+	csvQuote := '"'
+
+	// I. Read the whole input at once.  Tried stream reading with io.Pipe but… buffer!
+	allData, _ := io.ReadAll(*input)
+	readerCloneA := strings.NewReader(string(allData))
+	readerCloneB := strings.NewReader(string(allData))
+
+	// I.a Detect the delimiter between values in the input (default is comma `,`)
+	delimiterDetector := detector.New()
+	delimiters := delimiterDetector.DetectDelimiter(readerCloneA, byte(csvQuote))
+	if 0 < len(delimiters) {
+		csvDelimiter = readFirstRune(delimiters[0])
+	}
+	if 1 < len(delimiters) {
+		err = fmt.Errorf("too many delimiters: found `%s` and `%s`", delimiters[0], delimiters[1])
+		return
+	}
 
-	// I. Read the whole input at once.  Stream reading ?  Perhaps someday ?
-	csvRows, errReader := csv.NewReader(*input).ReadAll()
+	// I.b Read the actual CSV contents
+	csvReader := csv.NewReader(readerCloneB)
+	csvReader.Comma = csvDelimiter
+	csvRows, errReader := csvReader.ReadAll()
 	if errReader != nil {
 		err = errors.New("Failed to read input CSV: " + errReader.Error())
 		return
@@ -71,11 +93,6 @@ func (r CsvTallyReader) Read(input *io.Reader) (
 		}
 	}
 
-	// Do we still need this?  Right now we should be ok.
-	//for gradeIndex, grade := range grades {
-	//	grades[gradeIndex] = strings.TrimSpace(grade)
-	//}
-
 	return
 }
 

reader/reader.go

@@ -83,3 +83,11 @@ func GenerateDummyGradeNames(thatMany int) (grades []string, err error) {
 
 	return
 }
+
+func readFirstRune(str string) (first rune) {
+	for _, someRune := range str {
+		first = someRune
+		break
+	}
+	return
+}