1 files changed, 42 insertions, 0 deletions
diff --git a/grammar/src/abnf/boolean_fns.rs b/grammar/src/abnf/boolean_fns.rs
new file mode 100644
index 0000000..08f317c
--- /dev/null
+++ b/grammar/src/abnf/boolean_fns.rs
@@ -0,0 +1,42 @@
+//! This file collects some functions that return a boolean value from
+//! a character.
+
+pub(super) fn is_wsp(c: char) -> bool {
+    c == ' ' || c == '\t'
+}
+
+pub(crate) fn is_v_char(c: char) -> bool {
+    ('!'..='~').contains(&c)
+}
+
+pub(super) fn is_wsp_or_v_char(c: char) -> bool {
+    is_wsp(c) || is_v_char(c)
+}
+
+pub(super) fn is_not_newline(c: char) -> bool {
+    c != '\n' && c != '\r'
+}
+
+pub(super) fn is_alpha(c: char) -> bool {
+    c.is_ascii_alphabetic()
+}
+
+pub(super) fn is_decimal_digit(c: char) -> bool {
+    c.is_ascii_digit()
+}
+
+pub(super) fn is_binary_digit(c: char) -> bool {
+    c == '0' || c == '1'
+}
+
+pub(super) fn is_hexadecimal_digit(c: char) -> bool {
+    is_decimal_digit(c) || ('A'..='F').contains(&c) || ('a'..='f').contains(&c)
+}
+
+pub(super) fn is_alpha_or_digit_or_hyphen(c: char) -> bool {
+    is_alpha(c) || is_decimal_digit(c) || c == '-'
+}
+
+pub(super) fn is_char_value(c: char) -> bool {
+    (' '..='~').contains(&c) && c != '"'
+}