2 files changed, 134 insertions, 0 deletions
diff --git a/src/lexer/lexed.zig b/src/lexer/lexed.zig
new file mode 100644
index 0000000..3134705
--- /dev/null
+++ b/src/lexer/lexed.zig
@@ -0,0 +1,47 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+
+pub const Kind = enum {
+    literal,
+    delimiter,
+    operator,
+
+    const Self = @This();
+
+    pub fn string(self: *Self) []const u8 {
+        switch (*self) {
+            .literal => return "literal",
+            .delimiter => return "delimiter",
+            .operator => return "operator",
+        }
+    }
+};
+
+pub const Lexed = struct {
+    allocator: Allocator,
+    kind: Kind,
+    content: std.ArrayList(u8),
+
+    const Self = @This();
+
+    pub fn init(alloc: Allocator, kind: Kind, content: std.ArrayList(u8)) Lexed {
+        return Lexed{
+            .allocator = alloc,
+            .kind = kind,
+            .content = content,
+        };
+    }
+
+    pub fn deinit(self: *Self) void {
+        self.content.deinit(self.allocator);
+    }
+
+    pub fn clone(self: *const Self, alloc: Allocator) Allocator.Error!std.ArrayList(u8) {
+        return self.content.clone(alloc);
+    }
+
+    pub fn equals(self: *const Self, kind: Kind, content: []const u8) bool {
+        if (self.kind != kind) return false;
+        return std.mem.eql(u8, self.content.items, content);
+    }
+};
diff --git a/src/lexer/lexer.zig b/src/lexer/lexer.zig
new file mode 100644
index 0000000..8488a16
--- /dev/null
+++ b/src/lexer/lexer.zig
@@ -0,0 +1,87 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const unicode = std.unicode;
+const lexed = @import("lexed.zig");
+
+const operators = [_][]const u8{ "*", "_", "`", "<", ">", ":", "!", "[", "]", "(", ")", "$", "-", "." };
+const delimiters = [_][]const u8{"\n"};
+
+pub const Lexer = struct {
+    iter: unicode.Utf8Iterator,
+    force_lit: bool = false,
+
+    const Self = @This();
+
+    pub const Error = error{
+        InvalidUtf8,
+    } || Allocator.Error;
+
+    pub fn init(content: []const u8) Error!Lexer {
+        const view = try unicode.Utf8View.init(content);
+        return .{ .iter = view.iterator() };
+    }
+
+    pub fn next(self: *Self, alloc: Allocator) Error!?lexed.Lexed {
+        var acc = try std.ArrayList(u8).initCapacity(alloc, 2);
+        errdefer acc.deinit(alloc);
+
+        var current_kind: ?lexed.Kind = null;
+        while (self.iter.nextCodepointSlice()) |rune| {
+            if (std.mem.eql(u8, rune, "\r")) continue;
+            // escape chars
+            if (std.mem.eql(u8, rune, "\\")) {
+                self.force_lit = true;
+                current_kind = .literal;
+            } else {
+                current_kind = self.getCurrentKind(rune); 
+                self.force_lit = false;
+                try acc.appendSlice(alloc, rune);
+            }
+            // conds here to avoid creating complex condition in while
+            const next_rune = self.iter.peek(1);
+            if (next_rune.len > 0) {
+                if (self.getCurrentKind(next_rune) != current_kind.?) break;
+            }
+        }
+        const kind = current_kind orelse {
+            acc.deinit(alloc);
+            return null;
+        };
+        return lexed.Lexed.init(alloc, kind, acc);
+    }
+
+    fn getCurrentKind(self: *Self, rune: []const u8) ?lexed.Kind {
+        if (self.force_lit) return .literal;
+        if (isIn(&operators, rune)) {
+            return .operator;
+        } else if (isIn(&delimiters, rune)) {
+            return .delimiter;
+        }
+        return .literal;
+    }
+};
+
+fn isIn(arr: []const []const u8, v: []const u8) bool {
+    for (arr) |it| if (std.mem.eql(u8, it, v)) return true;
+    return false;
+}
+
+test "literal" {
+    const expect = std.testing.expect;
+
+    var arena = std.heap.DebugAllocator(.{}){};
+    defer _ = arena.deinit();
+    const alloc = arena.allocator();
+
+    var l = try Lexer.init("hello world :)");
+
+    var first = (try l.next(alloc)).?;
+    defer first.deinit();
+    try expect(first.equals(.literal, "hello world "));
+
+    var second = (try l.next(alloc)).?;
+    defer second.deinit();
+    try expect(second.equals(.operator, ":)"));
+
+    try expect(try l.next(alloc) == null);
+}