2 files changed, 170 insertions, 0 deletions
diff --git a/mintages/errors.go b/mintages/errors.go
new file mode 100644
index 0000000..a456c1a
--- /dev/null
+++ b/mintages/errors.go
@@ -0,0 +1,46 @@
+package mintages
+
+import "fmt"
+
+type location struct {
+	file   string
+	linenr int
+}
+
+func (loc location) String() string {
+	return fmt.Sprintf("%s: %d", loc.file, loc.linenr)
+}
+
+type BadTokenError struct {
+	location
+	token string
+}
+
+func (e BadTokenError) Error() string {
+	return fmt.Sprintf("%s: unknown token ‘%s’", e.location, e.linenr, e.token)
+}
+
+type ArgCountMismatchError struct {
+	location
+	token         string
+	expected, got int
+}
+
+func (e ArgCountMismatchError) Error() string {
+	var suffix string
+	if e.expected != 1 {
+		suffix = "s"
+	}
+	return fmt.Sprintf("%s: ‘%s’ token expects %d argument%s but got %d",
+		e.location, e.token, e.expected, suffix, e.got)
+}
+
+type SyntaxError struct {
+	location
+	expected, got string
+}
+
+func (e SyntaxError) Error() string {
+	return fmt.Sprintf("%s: syntax error: expected %s but got %s",
+		e.location, e.expected, e.got)
+}
diff --git a/mintages/parser.go b/mintages/parser.go
new file mode 100644
index 0000000..5c83713
--- /dev/null
+++ b/mintages/parser.go
@@ -0,0 +1,124 @@
+package mintages
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+	"unicode"
+)
+
+type coinset [8]int
+
+type Data struct {
+	StartYear       int
+	Circ, Bu, Proof []coinset
+}
+
+func ForCountry(code string) (Data, error) {
+	path := filepath.Join("data", "mintages", code)
+	f, err := os.Open(path)
+	if err != nil {
+		return Data{}, err
+	}
+	defer f.Close()
+	scanner := bufio.NewScanner(f)
+
+	var (
+		data  Data       // Our data struct
+		slice *[]coinset // Where to append mintages
+	)
+
+	for linenr := 1; scanner.Scan(); linenr++ {
+		line := scanner.Text()
+		tokens := strings.FieldsFunc(strings.TrimSpace(line), unicode.IsSpace)
+
+		switch {
+		case len(tokens) == 0:
+			continue
+		case tokens[0] == "BEGIN":
+			if len(tokens) != 2 {
+				return Data{}, ArgCountMismatchError{
+					token:    tokens[0],
+					expected: 1,
+					got:      len(tokens) - 1,
+					location: location{path, 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 Data{}, SyntaxError{
+						expected: "‘CIRC’, ‘BU’, ‘PROOF’, or a year",
+						got:      arg,
+						location: location{path, linenr},
+					}
+				}
+				data.StartYear, _ = strconv.Atoi(arg)
+			}
+		case isNumeric(tokens[0], true):
+			numcoins := len(coinset{})
+			tokcnt := len(tokens)
+
+			if tokcnt != numcoins {
+				return Data{}, SyntaxError{
+					expected: fmt.Sprintf("%d mintage entries", numcoins),
+					got:      fmt.Sprintf("%d entries", tokcnt),
+					location: location{path, linenr},
+				}
+			}
+
+			var row coinset
+			for i, tok := range tokens {
+				row[i], _ = strconv.Atoi(strings.ReplaceAll(tok, ".", ""))
+			}
+			*slice = append(*slice, row)
+		default:
+			return Data{}, BadTokenError{
+				token:    tokens[0],
+				location: location{path, linenr},
+			}
+		}
+	}
+
+	/* Pad rows of ‘unknown’ mintages at the end of each set of mintages
+	   for each year that we haven’t filled in info for. This avoids
+	   things accidentally breaking if the new year comes and we forget
+	   to add extra rows. */
+	for _, ms := range [...]*[]coinset{&data.Circ, &data.Bu, &data.Proof} {
+		finalYear := len(*ms) + data.StartYear - 1
+		missing := time.Now().Year() - finalYear
+		for i := 0; i < missing; i++ {
+			*ms = append(*ms, coinset{-1, -1, -1, -1, -1, -1, -1, -1})
+		}
+	}
+
+	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':
+		case '.':
+			if !dot {
+				return false
+			}
+		default:
+			return false
+		}
+	}
+	return true
+}