mime: extract string parser

src/str/parser.zig

@@ -0,0 +1,88 @@
+// some utils to parser strings.
+const std = @import("std");
+const testing = std.testing;
+
+pub const Reader = struct {
+    s: []const u8,
+    i: usize = 0,
+
+    pub fn until(self: *Reader, c: u8) []const u8 {
+        const ln = self.s.len;
+        const start = self.i;
+        while (self.i < ln) {
+            if (c == self.s[self.i]) return self.s[start..self.i];
+            self.i += 1;
+        }
+
+        return self.s[start..self.i];
+    }
+
+    pub fn tail(self: *Reader) []const u8 {
+        if (self.i > self.s.len) return "";
+        defer self.i = self.s.len;
+        return self.s[self.i..];
+    }
+
+    pub fn skip(self: *Reader) bool {
+        if (self.i >= self.s.len) return false;
+        self.i += 1;
+        return true;
+    }
+};
+
+test "Reader.skip" {
+    var r = Reader{ .s = "foo" };
+    try testing.expect(r.skip());
+    try testing.expect(r.skip());
+    try testing.expect(r.skip());
+    try testing.expect(!r.skip());
+    try testing.expect(!r.skip());
+}
+
+test "Reader.tail" {
+    var r = Reader{ .s = "foo" };
+    try testing.expectEqualStrings("foo", r.tail());
+    try testing.expectEqualStrings("", r.tail());
+}
+
+test "Reader.until" {
+    var r = Reader{ .s = "foo.bar.baz" };
+    try testing.expectEqualStrings("foo", r.until('.'));
+    _ = r.skip();
+    try testing.expectEqualStrings("bar", r.until('.'));
+    _ = r.skip();
+    try testing.expectEqualStrings("baz", r.until('.'));
+
+    r = Reader{ .s = "foo" };
+    try testing.expectEqualStrings("foo", r.until('.'));
+
+    r = Reader{ .s = "" };
+    try testing.expectEqualStrings("", r.until('.'));
+}
+
+pub fn trim(s: []const u8) []const u8 {
+    const ln = s.len;
+    if (ln == 0) {
+        return "";
+    }
+    var start: usize = 0;
+    while (start < ln) {
+        if (!std.ascii.isWhitespace(s[start])) break;
+        start += 1;
+    }
+
+    var end: usize = ln;
+    while (end > 0) {
+        if (!std.ascii.isWhitespace(s[end - 1])) break;
+        end -= 1;
+    }
+
+    return s[start..end];
+}
+
+test "trim" {
+    try testing.expectEqualStrings("", trim(""));
+    try testing.expectEqualStrings("foo", trim("foo"));
+    try testing.expectEqualStrings("foo", trim(" \n\tfoo"));
+    try testing.expectEqualStrings("foo", trim("foo \n\t"));
+}