Unmarshal ints and floats

internal/ast/decode.go

@@ -0,0 +1,113 @@
+package ast
+
+import (
+	"errors"
+	"math"
+	"strconv"
+	"strings"
+)
+
+func parseFloat(b []byte) (float64, error) {
+	// TODO: inefficient
+	if len(b) == 4 && (b[0] == '+' || b[0] == '-') && b[1] == 'n' && b[2] == 'a' && b[3] == 'n' {
+		return math.NaN(), nil
+	}
+
+	tok := string(b)
+	err := numberContainsInvalidUnderscore(tok)
+	if err != nil {
+		return 0, err
+	}
+	cleanedVal := cleanupNumberToken(tok)
+	return strconv.ParseFloat(cleanedVal, 64)
+}
+
+func parseIntHex(b []byte) (int64, error) {
+	tok := string(b)
+	cleanedVal := cleanupNumberToken(tok)
+	err := hexNumberContainsInvalidUnderscore(cleanedVal)
+	if err != nil {
+		return 0, nil
+	}
+	return strconv.ParseInt(cleanedVal[2:], 16, 64)
+}
+
+func parseIntOct(b []byte) (int64, error) {
+	tok := string(b)
+	cleanedVal := cleanupNumberToken(tok)
+	err := numberContainsInvalidUnderscore(cleanedVal)
+	if err != nil {
+		return 0, err
+	}
+	return strconv.ParseInt(cleanedVal[2:], 8, 64)
+}
+
+func parseIntBin(b []byte) (int64, error) {
+	tok := string(b)
+	cleanedVal := cleanupNumberToken(tok)
+	err := numberContainsInvalidUnderscore(cleanedVal)
+	if err != nil {
+		return 0, err
+	}
+	return strconv.ParseInt(cleanedVal[2:], 2, 64)
+}
+
+func parseIntDec(b []byte) (int64, error) {
+	tok := string(b)
+	cleanedVal := cleanupNumberToken(tok)
+	err := numberContainsInvalidUnderscore(cleanedVal)
+	if err != nil {
+		return 0, err
+	}
+	return strconv.ParseInt(cleanedVal, 10, 64)
+}
+
+func numberContainsInvalidUnderscore(value string) error {
+	// For large numbers, you may use underscores between digits to enhance
+	// readability. Each underscore must be surrounded by at least one digit on
+	// each side.
+
+	hasBefore := false
+	for idx, r := range value {
+		if r == '_' {
+			if !hasBefore || idx+1 >= len(value) {
+				// can't end with an underscore
+				return errInvalidUnderscore
+			}
+		}
+		hasBefore = isDigitRune(r)
+	}
+	return nil
+}
+
+func hexNumberContainsInvalidUnderscore(value string) error {
+	hasBefore := false
+	for idx, r := range value {
+		if r == '_' {
+			if !hasBefore || idx+1 >= len(value) {
+				// can't end with an underscore
+				return errInvalidUnderscoreHex
+			}
+		}
+		hasBefore = isHexDigit(r)
+	}
+	return nil
+}
+
+func cleanupNumberToken(value string) string {
+	cleanedVal := strings.Replace(value, "_", "", -1)
+	return cleanedVal
+}
+
+func isHexDigit(r rune) bool {
+	return isDigitRune(r) ||
+		(r >= 'a' && r <= 'f') ||
+		(r >= 'A' && r <= 'F')
+}
+
+func isDigitRune(r rune) bool {
+	return r >= '0' && r <= '9'
+}
+
+var errInvalidUnderscore = errors.New("invalid use of _ in number")
+var errInvalidUnderscoreHex = errors.New("invalid use of _ in hex number")