1 files changed, 204 insertions, 0 deletions
diff --git a/mintage/parser.go b/mintage/parser.go
new file mode 100644
index 0000000..242a3bb
--- /dev/null
+++ b/mintage/parser.go
@@ -0,0 +1,204 @@
+package mintage
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+	"unicode"
+)
+
+const (
+	_       = -iota
+	Unknown // Unknown mintage
+	Invalid // All mintages <= than this are invalid
+)
+
+type SyntaxError struct {
+	expected, got string
+	file          string
+	linenr        int
+}
+
+func (e SyntaxError) Error() string {
+	return fmt.Sprintf("%s:%d: syntax error: expected %s but got %s",
+		e.file, e.linenr, e.expected, e.got)
+}
+
+type Row struct {
+	Label string
+	Cols  [8]int
+}
+
+type Set struct {
+	StartYear       int
+	Circ, BU, Proof []Row
+}
+
+func Parse(reader io.Reader, file string) (Set, error) {
+	var (
+		data  Set    // Our data struct
+		slice *[]Row // Where to append mintages
+		year  int    // The current year we are at
+	)
+
+	scanner := bufio.NewScanner(reader)
+	for linenr := 1; scanner.Scan(); linenr++ {
+		var mintmark struct {
+			s    string
+			star bool
+		}
+
+		line := scanner.Text()
+		tokens := strings.FieldsFunc(strings.TrimSpace(line), unicode.IsSpace)
+
+		switch {
+		case len(tokens) == 0:
+			continue
+		case tokens[0] == "BEGIN":
+			if len(tokens)-1 != 1 {
+				return Set{}, SyntaxError{
+					expected: "single argument to ‘BEGIN’",
+					got:      fmt.Sprintf("%d arguments", len(tokens)-1),
+					file:     file,
+					linenr:   linenr,
+				}
+			}
+
+			arg := tokens[1]
+
+			switch arg {
+			case "CIRC":
+				slice = &data.Circ
+			case "BU":
+				slice = &data.BU
+			case "PROOF":
+				slice = &data.Proof
+			default:
+				if !isNumeric(arg, false) {
+					return Set{}, SyntaxError{
+						expected: "‘CIRC’, ‘BU’, ‘PROOF’, or a year",
+						got:      arg,
+						file:     file,
+						linenr:   linenr,
+					}
+				}
+				data.StartYear, _ = strconv.Atoi(arg)
+			}
+
+			year = data.StartYear - 1
+		case isLabel(tokens[0]):
+			n := len(tokens[0])
+			if n > 2 && tokens[0][n-2] == '*' {
+				mintmark.star = true
+				mintmark.s = tokens[0][:n-2]
+			} else {
+				mintmark.s = tokens[0][:n-1]
+			}
+			tokens = tokens[1:]
+			if !isNumeric(tokens[0], true) && tokens[0] != "?" {
+				return Set{}, SyntaxError{
+					expected: "mintage row after label",
+					got:      tokens[0],
+					file:     file,
+					linenr:   linenr,
+				}
+			}
+			fallthrough
+		case isNumeric(tokens[0], true), tokens[0] == "?":
+			switch {
+			case slice == nil:
+				return Set{}, SyntaxError{
+					expected: "coin type declaration",
+					got:      tokens[0],
+					file:     file,
+					linenr:   linenr,
+				}
+			case data.StartYear == 0:
+				return Set{}, SyntaxError{
+					expected: "start year declaration",
+					got:      tokens[0],
+					file:     file,
+					linenr:   linenr,
+				}
+			}
+
+			numcoins := len(Row{}.Cols)
+			tokcnt := len(tokens)
+
+			if tokcnt != numcoins {
+				word := "entries"
+				if tokcnt == 1 {
+					word = "entry"
+				}
+				return Set{}, SyntaxError{
+					expected: fmt.Sprintf("%d mintage entries", numcoins),
+					got:      fmt.Sprintf("%d %s", tokcnt, word),
+					file:     file,
+					linenr:   linenr,
+				}
+			}
+
+			var row Row
+			switch {
+			case mintmark.s == "":
+				year++
+				row.Label = strconv.Itoa(year)
+			case mintmark.star:
+				year++
+				fallthrough
+			default:
+				row.Label = fmt.Sprintf("%d %s", year, mintmark.s)
+			}
+
+			for i, tok := range tokens {
+				if tok == "?" {
+					row.Cols[i] = Unknown
+				} else {
+					row.Cols[i] = atoiWithDots(tok)
+				}
+			}
+			*slice = append(*slice, row)
+		default:
+			return Set{}, SyntaxError{
+				expected: "‘BEGIN’ directive or mintage row",
+				got:      fmt.Sprintf("invalid token ‘%s’", tokens[0]),
+				file:     file,
+				linenr:   linenr,
+			}
+		}
+	}
+
+	return data, nil
+}
+
+func isNumeric(s string, dot bool) bool {
+	for _, ch := range s {
+		switch ch {
+		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+		default:
+			if ch != '.' || !dot {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+func isLabel(s string) bool {
+	n := len(s)
+	return (n > 2 && s[n-1] == ':' && s[n-2] == '*') ||
+		(n > 1 && s[n-1] == ':')
+}
+
+func atoiWithDots(s string) int {
+	n := 0
+	for _, ch := range s {
+		if ch == '.' {
+			continue
+		}
+		n = n*10 + int(ch) - '0'
+	}
+	return n
+}