Add CSV-to-Markdown formatter v1

cmd/md-fmt/README.md

@@ -0,0 +1,7 @@
+# CSV to Markdown Table Formatter
+
+Takes a csv-like file as input and outputs a formatted markdown table with it.
+
+## Usage
+
+Run `md-fmt -help` for the list of command line arguments.

cmd/md-fmt/main.go

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+// md-fmt takes a csv or tsv input file and outputs a formatted markdown table
+// with the data.
+package main
+
+import (
+	"encoding/csv"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"strings"
+)
+
+var (
+	sourcePath = flag.String("source", "", "path to the input file")
+	separator  = flag.String("sep", ",", "separator character to use when reading the csv file")
+	lazyQuotes = flag.Bool("lazy-quotes", false, "controls the lazy-quotes setting on the csv reader")
+)
+
+func main() {
+	flag.Parse()
+
+	fd, err := os.Open(*sourcePath)
+	if err != nil {
+		log.Fatalf("failed to open source file %s: %s\n", *sourcePath, err)
+	}
+
+	sep := []rune(*separator)[0]
+	read := csv.NewReader(fd)
+	read.Comma = sep
+	read.TrimLeadingSpace = true
+	read.LazyQuotes = *lazyQuotes
+
+	records, err := read.ReadAll()
+	if err != nil {
+		log.Fatalf("failed to load records in memory: %s\n", err)
+	}
+
+	widths := make([]int, len(records[0]))
+	for _, row := range records {
+		for i, col := range row {
+			widths[i] = max(widths[i], len(col))
+		}
+	}
+
+	c := make([]string, len(records[0]))
+	log.Println(records[0], len(c))
+	for i := 0; i < len(c); i++ {
+		c[i] = " %-*s "
+	}
+	pattern := fmt.Sprintf("|%s|\n", strings.Join(c, "|"))
+	log.Println(pattern)
+
+	sb := strings.Builder{}
+
+	// Format header row
+	curr := make([]any, 0, 2*len(widths))
+	for i := range widths {
+		curr = append(curr, widths[i], records[0][i])
+	}
+	sb.WriteString(fmt.Sprintf(pattern, curr...))
+
+	// Format header separator row
+	curr = curr[:0] // empty slice but preserve capacity
+	for i := range widths {
+		curr = append(curr, widths[i], strings.Repeat("-", widths[i]))
+	}
+	sb.WriteString(fmt.Sprintf(pattern, curr...))
+
+	// Format rest of records
+	for i := 1; i < len(records); i++ {
+		curr = curr[:0]
+		for j := range widths {
+			curr = append(curr, widths[j], records[i][j])
+		}
+		sb.WriteString(fmt.Sprintf(pattern, curr...))
+	}
+
+	fmt.Print(sb.String())
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}