Start work on template package

src/template/lib.zig

@@ -0,0 +1,121 @@
+const std = @import("std");
+
+pub fn main() !void {
+    try execute(std.io.getStdOut().writer(), @embedFile("./test.tmp.html"), .{ .community = .{ .name = "abcd" } });
+}
+
+pub fn execute(writer: anytype, comptime template: []const u8, args: anytype) !void {
+    @setEvalBranchQuota(@intCast(u32, template.len * 6));
+    comptime var iter = TokenIter{ .text = template };
+    comptime var state: State = .text;
+    inline while (comptime iter.next()) |token| {
+        switch (token) {
+            .text => |text| switch (state) {
+                .text => try writer.writeAll(text),
+                else => @compileError("Text token not allowed in state " ++ @tagName(state) ++ text),
+            },
+            .open_bracket => switch (state) {
+                .text => state = .template_start,
+                .template_start => {
+                    try writer.writeByte('{');
+                    state = .text;
+                },
+                else => @compileError(""),
+            },
+            .close_bracket => switch (state) {
+                .text => state = .text_close_bracket,
+                .text_close_bracket => {
+                    try writer.writeByte('}');
+                    state = .text;
+                },
+                .template_start, .template => state = .text,
+                //else => @compileError(""),
+            },
+            .whitespace => |wsp| switch (state) {
+                .text => try writer.writeAll(wsp),
+                else => {},
+            },
+            .period => switch (state) {
+                .text => try writer.writeByte('.'),
+                .template_start, .template => {
+                    try argDeref(writer, &iter, args);
+                    state = .template;
+                },
+                else => @compileError(""),
+            },
+        }
+    }
+}
+
+fn argDeref(writer: anytype, comptime iter: *TokenIter, arg: anytype) !void {
+    inline while (comptime iter.peek()) |token| {
+        switch (token) {
+            .period => {},
+            .text => |text| {
+                _ = comptime iter.next();
+                return argDeref(writer, iter, @field(arg, text));
+            },
+            else => return try writer.writeAll(arg),
+        }
+        _ = comptime iter.next();
+    }
+}
+
+const State = enum {
+    text,
+    text_close_bracket,
+    template_start,
+    template,
+};
+
+const Token = union(enum) {
+    text: []const u8,
+    open_bracket: void,
+    close_bracket: void,
+    period: void,
+    whitespace: []const u8,
+};
+
+const TokenIter = struct {
+    start: usize = 0,
+    text: []const u8,
+    peeked_token: ?Token = null,
+
+    fn next(self: *TokenIter) ?Token {
+        if (self.peeked_token) |token| {
+            self.peeked_token = null;
+            return token;
+        }
+
+        const remaining = self.text[self.start..];
+        if (remaining.len == 0) return null;
+
+        const ch = remaining[0];
+        self.start += 1;
+        switch (ch) {
+            '{' => return .{ .open_bracket = {} },
+            '}' => return .{ .close_bracket = {} },
+            '.' => return .{ .period = {} },
+            ' ', '\t', '\n', '\r' => {
+                var idx: usize = 0;
+                while (idx < remaining.len and std.mem.indexOfScalar(u8, " \t\n\r", remaining[idx]) != null) : (idx += 1) {}
+
+                self.start += idx - 1;
+                return .{ .whitespace = remaining[0..idx] };
+            },
+            else => {
+                var idx: usize = 0;
+                while (idx < remaining.len and std.mem.indexOfScalar(u8, "{}. \t\n\r", remaining[idx]) == null) : (idx += 1) {}
+
+                self.start += idx - 1;
+                return .{ .text = remaining[0..idx] };
+            },
+        }
+    }
+
+    fn peek(self: *TokenIter) ?Token {
+        const token = self.next();
+        self.peeked_token = token;
+        return token;
+    }
+};

src/template/test.tmp.html

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+<!DOCTYPE html>
+<html>
+  <head>
+    <title>{ .community.name }</title>
+  </head>
+
+  <body>
+    <h1> TITLE </h1>
+    <h2> {{ REAL BRACKETS }} </h2>
+
+    <section>
+      {{#for args.notes |$note, $i|}}
+        <h3>Note no. {{$i}}</h3>
+        {{#template note_display ($note)}}
+      {{/for}}
+    </section>
+  </body>
+</html>