1 files changed, 47 insertions, 0 deletions

diff --git a/src/eval/html/html.zig b/src/eval/html/html.zig
new file mode 100644
index 0000000..064ebb1
--- /dev/null
+++ b/src/eval/html/html.zig
@@ -0,0 +1,47 @@
+const std = @import("std");
+const eql = std.mem.eql;
+
+pub const Error = error{InvalidUtf8} || std.mem.Allocator.Error;
+
+pub fn escape(alloc: std.mem.Allocator, v: []const u8) Error![]const u8 {
+    var acc = try std.ArrayList(u8).initCapacity(alloc, v.len);
+    errdefer acc.deinit(alloc);
+    const view = try std.unicode.Utf8View.init(v);
+    var iter = view.iterator();
+    while (iter.nextCodepointSlice()) |rune| {
+        if (eql(u8, rune, "&")) {
+            try acc.appendSlice(alloc, "&");
+        } else if (eql(u8, rune, "'")) {
+            try acc.appendSlice(alloc, "'");
+        } else if (eql(u8, rune, "<")) {
+            try acc.appendSlice(alloc, "&lt;");
+        } else if (eql(u8, rune, ">")) {
+            try acc.appendSlice(alloc, "&gt;");
+        } else if (eql(u8, rune, "\"")) {
+            try acc.appendSlice(alloc, "&#34;");
+        } else {
+            try acc.appendSlice(alloc, rune);
+        }
+    }
+    return acc.toOwnedSlice(alloc);
+}
+
+fn doTest(alloc: std.mem.Allocator, el: []const u8, exp: []const u8) !void {
+    const got = try escape(alloc, el);
+    defer alloc.free(got);
+    std.testing.expect(eql(u8, got, exp)) catch |err| {
+        std.debug.print("{s}\n", .{got});
+        return err;
+    };
+}
+
+test "escaping html" {
+    const alloc = std.testing.allocator;
+
+    try doTest(alloc, "hello world", "hello world");
+    try doTest(alloc, "hello&world", "hello&amp;world");
+    try doTest(alloc, "hello'world", "hello&#39;world");
+    try doTest(alloc, "hello<world", "hello&lt;world");
+    try doTest(alloc, "hello>world", "hello&gt;world");
+    try doTest(alloc, "hello\"world", "hello&#34;world");
+}