feat(ast): parse content

1 files changed, 84 insertions, 0 deletions

diff --git a/src/ast.zig b/src/ast.zig
new file mode 100644
index 0000000..94bb2c5
--- /dev/null
+++ b/src/ast.zig
@@ -0,0 +1,84 @@
+const std = @import("std");
+const Lexed = @import("lexer/Lexed.zig");
+const Lexer = @import("lexer/Lexer.zig");
+const Element = @import("dom/Element.zig");
+const Allocator = std.mem.Allocator;
+
+pub const Error = error{
+    InvalidSequence,
+    UnclosedModifier,
+    FeatureNotSupported,
+} || Lexer.Error;
+
+pub fn parse(parent: Allocator, content: []const u8) Error![]const u8 {
+    var arena = std.heap.ArenaAllocator.init(parent);
+    defer arena.deinit();
+    const alloc = arena.allocator();
+
+    var elements = try std.ArrayList(Element).initCapacity(alloc, 2);
+
+    var l = try Lexer.init(content);
+    while (l.nextKind()) |it| {
+        switch (it) {
+            .literal, .bold, .italic, .code => try elements.append(alloc, try parseContent(alloc, &l)),
+            else => return Error.FeatureNotSupported,
+        }
+    }
+
+    var res = try std.ArrayList(u8).initCapacity(parent, elements.items.len);
+    for (elements.items) |it| {
+        var v = it;
+        try res.appendSlice(parent, try v.render(alloc));
+    }
+    return res.toOwnedSlice(parent);
+}
+
+fn parseContent(alloc: Allocator, l: *Lexer) Error!Element {
+    var content = Element.initEmpty(alloc);
+    const v = (try l.next(alloc)).?;
+    switch (v.kind) {
+        .literal => {
+            const el = try Element.initLitEscaped(alloc, v.content.items);
+            try content.appendContent(el);
+        },
+        .bold => try content.appendContent(try parseModifier(alloc, l, .bold, "b")),
+        .italic => try content.appendContent(try parseModifier(alloc, l, .italic, "em")),
+        .code => try content.appendContent(try parseModifier(alloc, l, .code, "code")),
+        else => return Error.InvalidSequence,
+    }
+    return content;
+}
+
+fn parseModifier(alloc: Allocator, l: *Lexer, knd: Lexed.Kind, tag: []const u8) Error!Element {
+    var el = try Element.init(alloc, .content, tag);
+    while (l.nextKind()) |it| {
+        if (it == knd) {
+            // consuming the finisher
+            var v = (try l.next(alloc)).?;
+            v.deinit();
+            break;
+        }
+        if (it.isDelimiter()) return Error.UnclosedModifier;
+        try el.appendContent(try parseContent(alloc, l));
+    }
+    return el;
+}
+
+fn doTest(alloc: Allocator, t: []const u8, v: []const u8) !void {
+    const g = try parse(alloc, t);
+    defer alloc.free(g);
+    std.testing.expect(std.mem.eql(u8, g, v)) catch |err| {
+        std.debug.print("{s}\n", .{g});
+        return err;
+    };
+}
+
+test "parse content" {
+    var arena = std.heap.DebugAllocator(.{}).init;
+    defer if (arena.deinit() == .leak) std.debug.print("leaking!\n", .{});
+    const alloc = arena.allocator();
+
+    try doTest(alloc, "hello world", "hello world");
+    try doTest(alloc, "*hello* world", "<b>hello</b> world");
+    try doTest(alloc, "*he_ll_o* world", "<b>he<em>ll</em>o</b> world");
+}