Split up template parsing and execution
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3b03764be7
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7191ad8f27
2 changed files with 130 additions and 45 deletions
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@ -4,63 +4,141 @@ pub fn main() !void {
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try execute(std.io.getStdOut().writer(), @embedFile("./test.tmp.html"), .{ .community = .{ .name = "abcd" } });
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}
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const logging = false;
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pub fn execute(writer: anytype, comptime template: []const u8, args: anytype) !void {
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@setEvalBranchQuota(@intCast(u32, template.len * 6));
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comptime var iter = TokenIter{ .text = template };
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comptime var state: State = .text;
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inline while (comptime iter.next()) |token| {
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if (logging) @compileLog(token);
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switch (token) {
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.text => |text| switch (state) {
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.text => try writer.writeAll(text),
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else => @compileError("Text token not allowed in state " ++ @tagName(state) ++ text),
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},
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.open_bracket => switch (state) {
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.text => state = .template_start,
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.template_start => {
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.text => |text| try writer.writeAll(text),
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.open_bracket => {
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const next = comptime iter.peek() orelse @compileError("Unexpected end of template");
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if (next == .open_bracket) {
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try writer.writeByte('{');
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state = .text;
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_ = comptime iter.next();
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} else {
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const result = comptime parseStatement(iter);
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try executeStatement(writer, result.statement, args);
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iter = result.new_iter;
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}
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},
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else => @compileError(""),
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},
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.close_bracket => switch (state) {
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.text => state = .text_close_bracket,
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.text_close_bracket => {
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try writer.writeByte('}');
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state = .text;
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},
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.template_start, .template => state = .text,
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//else => @compileError(""),
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},
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.whitespace => |wsp| switch (state) {
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.text => try writer.writeAll(wsp),
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else => {},
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},
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.period => switch (state) {
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.text => try writer.writeByte('.'),
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.template_start, .template => {
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try argDeref(writer, &iter, args);
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state = .template;
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},
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else => @compileError(""),
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.close_bracket => {
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const next = comptime iter.next() orelse @compileError("Unexpected end of template");
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if (comptime next == .close_bracket) try writer.writeByte('}') else @compileError("Unpaired close bracket, did you mean \"}}\"?");
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},
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.whitespace => |wsp| try writer.writeAll(wsp),
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.period => try writer.writeByte('.'),
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.pound => try writer.writeByte('#'),
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}
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}
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}
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fn argDeref(writer: anytype, comptime iter: *TokenIter, arg: anytype) !void {
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inline while (comptime iter.peek()) |token| {
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switch (token) {
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.period => {},
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.text => |text| {
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_ = comptime iter.next();
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return argDeref(writer, iter, @field(arg, text));
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fn executeStatement(writer: anytype, comptime stmt: Statement, args: anytype) !void {
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switch (stmt) {
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.expression => |expr| switch (expr) {
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.arg_deref => |fields| try argDeref(writer, fields, args),
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},
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else => return try writer.writeAll(arg),
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}
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_ = comptime iter.next();
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else => @compileError("TODO"),
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}
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}
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fn argDeref(writer: anytype, comptime names: []const []const u8, arg: anytype) !void {
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if (names.len == 0) {
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const T = @TypeOf(arg);
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if (comptime std.meta.trait.isZigString(T)) return writer.writeAll(arg);
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return std.fmt.format(writer, "{any}", .{arg});
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}
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return argDeref(writer, names[1..], @field(arg, names[0]));
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}
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fn parseStatement(comptime tokens: TokenIter) StatementResult {
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comptime {
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var iter = tokens;
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while (iter.next()) |token| switch (token) {
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.whitespace => {},
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.pound => {
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const next = iter.next() orelse @compileError("Unexpected end of template");
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if (logging) @compileLog("keyword", next);
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if (next != .text) @compileError("Expected keyword following '#' character");
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const text = next.text;
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const keyword = std.meta.stringToEnum(Keyword, text) orelse @compileError("Unknown keyword: " ++ text);
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_ = keyword;
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@panic("todo");
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},
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.period => {
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const expr = parseArgDeref(iter);
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iter = expr.new_iter;
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while (iter.next()) |it| switch (it) {
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.whitespace => {},
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.close_bracket => break,
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else => @compileError("TODO"),
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};
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return .{ .new_iter = iter, .statement = .{
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.expression = expr.expression,
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} };
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},
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else => @compileError(""),
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};
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@compileError("Unexpected end of template");
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}
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}
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fn parseArgDeref(comptime tokens: TokenIter) ExpressionResult {
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comptime {
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var iter = tokens;
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var fields: []const []const u8 = &.{};
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var wants = .text;
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while (iter.peek()) |token| {
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switch (token) {
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.whitespace => {},
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.text => |text| {
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if (wants != .text) @compileError("Unexpected token \"" ++ text ++ "\"");
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fields = fields ++ [1][]const u8{text};
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wants = .period;
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},
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.period => {
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if (wants != .period) @compileError("Unexpected token \".\"");
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wants = .text;
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},
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else => if (wants == .period) return .{
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.new_iter = iter,
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.expression = .{ .arg_deref = fields },
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} else @compileError("Unexpected token"),
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}
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_ = iter.next();
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}
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}
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}
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const Expression = union(enum) {
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arg_deref: []const []const u8,
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};
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const ExpressionResult = struct {
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new_iter: TokenIter,
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expression: Expression,
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};
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const Statement = union(enum) {
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expression: Expression,
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for_loop: struct {
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subtemplate: []const u8,
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indexable: Expression,
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iteration_capture: []const u8,
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index_capture: ?[]const u8,
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},
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};
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const StatementResult = struct {
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new_iter: TokenIter,
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statement: Statement,
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};
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const State = enum {
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text,
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text_close_bracket,
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@ -68,12 +146,17 @@ const State = enum {
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template,
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};
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const Keyword = enum {
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@"for",
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};
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const Token = union(enum) {
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text: []const u8,
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open_bracket: void,
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close_bracket: void,
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period: void,
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whitespace: []const u8,
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pound: void,
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};
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const TokenIter = struct {
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@ -96,6 +179,7 @@ const TokenIter = struct {
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'{' => return .{ .open_bracket = {} },
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'}' => return .{ .close_bracket = {} },
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'.' => return .{ .period = {} },
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'#' => return .{ .pound = {} },
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' ', '\t', '\n', '\r' => {
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var idx: usize = 0;
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while (idx < remaining.len and std.mem.indexOfScalar(u8, " \t\n\r", remaining[idx]) != null) : (idx += 1) {}
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@ -105,7 +189,7 @@ const TokenIter = struct {
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},
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else => {
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var idx: usize = 0;
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while (idx < remaining.len and std.mem.indexOfScalar(u8, "{}. \t\n\r", remaining[idx]) == null) : (idx += 1) {}
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while (idx < remaining.len and std.mem.indexOfScalar(u8, "{}.# \t\n\r", remaining[idx]) == null) : (idx += 1) {}
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self.start += idx - 1;
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return .{ .text = remaining[0..idx] };
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@ -1,7 +1,7 @@
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<!DOCTYPE html>
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<html>
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<head>
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<title>{ .community.name }</title>
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<title>{.community.name}</title>
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</head>
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<body>
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@ -9,10 +9,11 @@
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<h2> {{ REAL BRACKETS }} </h2>
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<section>
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{{#for .community}}
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{{#for args.notes |$note, $i|}}
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<h3>Note no. {{$i}}</h3>
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{{#template note_display ($note)}}
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{{/for}}
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{{#end}}
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</section>
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</body>
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</html>
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