url: implement query parsing

src/url/query.zig

@@ -0,0 +1,159 @@
+const std = @import("std");
+
+const Reader = @import("../str/parser.zig").Reader;
+
+// Values is a map with string key of string values.
+pub const Values = struct {
+    alloc: std.mem.Allocator,
+    map: std.StringArrayHashMapUnmanaged(List),
+
+    const List = std.ArrayListUnmanaged([]const u8);
+
+    pub fn init(alloc: std.mem.Allocator) Values {
+        return .{
+            .alloc = alloc,
+            .map = .{},
+        };
+    }
+
+    pub fn deinit(self: *Values) void {
+        var it = self.map.iterator();
+        while (it.next()) |entry| {
+            for (entry.value_ptr.items) |v| self.alloc.free(v);
+            entry.value_ptr.deinit(self.alloc);
+            self.alloc.free(entry.key_ptr.*);
+        }
+        self.map.deinit(self.alloc);
+    }
+
+    // add the key value couple to the values.
+    // the key and the value are duplicated.
+    pub fn append(self: *Values, k: []const u8, v: []const u8) !void {
+        const vv = try self.alloc.dupe(u8, v);
+
+        if (self.map.getPtr(k)) |list| {
+            return try list.append(self.alloc, vv);
+        }
+
+        const kk = try self.alloc.dupe(u8, k);
+        var list = List{};
+        try list.append(self.alloc, vv);
+        try self.map.put(self.alloc, kk, list);
+    }
+
+    pub fn get(self: *Values, k: []const u8) [][]const u8 {
+        if (self.map.get(k)) |list| {
+            return list.items;
+        }
+
+        return &[_][]const u8{};
+    }
+
+    pub fn first(self: *Values, k: []const u8) []const u8 {
+        if (self.map.getPtr(k)) |list| {
+            if (list.items.len == 0) return "";
+            return list.items[0];
+        }
+
+        return "";
+    }
+
+    pub fn delete(self: *Values, k: []const u8) void {
+        if (self.map.getPtr(k)) |list| {
+            list.deinit(self.alloc);
+            _ = self.map.fetchSwapRemove(k);
+        }
+    }
+
+    pub fn deleteValue(self: *Values, k: []const u8, v: []const u8) void {
+        const list = self.map.getPtr(k) orelse return;
+
+        var i: usize = 0;
+        while (i < list.items.len) {
+            if (std.mem.eql(u8, v, list.items[i])) {
+                _ = list.swapRemove(i);
+                return;
+            }
+            i += 1;
+        }
+    }
+
+    pub fn count(self: *Values) usize {
+        return self.map.count();
+    }
+};
+
+// Parse the given query.
+pub fn parseQuery(alloc: std.mem.Allocator, s: []const u8) !Values {
+    var values = Values.init(alloc);
+    errdefer values.deinit();
+
+    const ln = s.len;
+    if (ln == 0) return values;
+
+    var r = Reader{ .s = s };
+    while (true) {
+        const param = r.until('&');
+        if (param.len == 0) break;
+
+        var rr = Reader{ .s = param };
+        const k = rr.until('=');
+        if (k.len == 0) continue;
+
+        _ = rr.skip();
+        const v = rr.tail();
+
+        // TODO decode k and v
+
+        try values.append(k, v);
+
+        if (!r.skip()) break;
+    }
+
+    return values;
+}
+
+test "parse empty query" {
+    var values = try parseQuery(std.testing.allocator, "");
+    defer values.deinit();
+
+    try std.testing.expect(values.count() == 0);
+}
+
+test "parse empty query &" {
+    var values = try parseQuery(std.testing.allocator, "&");
+    defer values.deinit();
+
+    try std.testing.expect(values.count() == 0);
+}
+
+test "parse query" {
+    var values = try parseQuery(std.testing.allocator, "a=b&b=c");
+    defer values.deinit();
+
+    try std.testing.expect(values.count() == 2);
+    try std.testing.expect(values.get("a").len == 1);
+    try std.testing.expect(std.mem.eql(u8, values.get("a")[0], "b"));
+    try std.testing.expect(std.mem.eql(u8, values.first("a"), "b"));
+
+    try std.testing.expect(values.get("b").len == 1);
+    try std.testing.expect(std.mem.eql(u8, values.get("b")[0], "c"));
+    try std.testing.expect(std.mem.eql(u8, values.first("b"), "c"));
+}
+
+test "parse query no value" {
+    var values = try parseQuery(std.testing.allocator, "a");
+    defer values.deinit();
+
+    try std.testing.expect(values.count() == 1);
+    try std.testing.expect(std.mem.eql(u8, values.first("a"), ""));
+}
+
+test "parse query dup" {
+    var values = try parseQuery(std.testing.allocator, "a=b&a=c");
+    defer values.deinit();
+
+    try std.testing.expect(values.count() == 1);
+    try std.testing.expect(std.mem.eql(u8, values.first("a"), "b"));
+    try std.testing.expect(values.get("a").len == 2);
+}