621 lines
21 KiB
Zig
621 lines
21 KiB
Zig
const std = @import("std");
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pub fn main() !void {
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try execute(std.io.getStdOut().writer(), @embedFile("./test.tmp.html"), .{
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.community = .{ .name = "abcd" },
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.foo = [_][]const u8{ "5", "4", "3", "2", "1" },
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.baz = [_][]const []const u8{
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&.{ "5", "4", "3", "2", "1" },
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&.{ "5", "4", "3", "2", "1" },
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},
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.qux = true,
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.quxx = false,
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});
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}
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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 * 8));
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const tokens = comptime parseTemplateTokens(ControlTokenIter{ .text = template });
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const tmpl = comptime parseTemplate(tokens, 0, .root);
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try executeTemplate(writer, tmpl.item, args, .{});
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}
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fn executeTemplate(writer: anytype, comptime items: []const TemplateItem, args: anytype, captures: anytype) !void {
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inline for (items) |it| {
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switch (it) {
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.text => |text| try writer.writeAll(text),
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.statement => |stmt| try executeStatement(writer, stmt, args, captures),
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}
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}
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}
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fn executeStatement(writer: anytype, comptime stmt: Statement, args: anytype, captures: anytype) !void {
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switch (stmt) {
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.expression => |expr| {
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const val = evaluateExpression(expr, args, captures);
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try print(writer, val);
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},
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.@"for" => |loop| {
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const iterable = evaluateExpression(loop.header.iterable, args, captures);
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const subtemplate = loop.subtemplate;
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//std.log.debug("{any}", .{subtemplate});
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for (iterable) |v| {
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try executeTemplate(
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writer,
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subtemplate,
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args,
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addCapture(captures, loop.header.capture, v),
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);
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}
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},
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.@"if" => |if_stmt| {
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const condition = evaluateExpression(if_stmt.header.condition, args, captures);
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const subtemplate = if_stmt.subtemplate;
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if (condition) try executeTemplate(writer, subtemplate, args, captures);
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},
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//else => @compileError("TODO"),
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}
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}
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fn print(writer: anytype, arg: anytype) !void {
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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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if (comptime std.meta.trait.isNumber(T)) return std.fmt.format(writer, "{}", .{arg});
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@compileLog(@TypeOf(arg));
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@compileError("TODO");
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}
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fn Deref(comptime T: type, comptime names: []const []const u8) type {
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if (names.len == 0) return T;
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// Compiler segfaults when I use std.meta to get this info so we search it manually
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const field = for (@typeInfo(T).Struct.fields) |f| {
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if (std.mem.eql(u8, f.name, names[0])) break f;
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} else @compileError("Unknown field " ++ names[0] ++ " in type " ++ @typeName(T));
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return Deref(field.field_type, names[1..]);
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}
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fn deref(arg: anytype, comptime names: []const []const u8) Deref(@TypeOf(arg), names) {
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if (names.len == 0) return arg;
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return deref(@field(arg, names[0]), names[1..]);
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}
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fn EvaluateExpression(comptime expression: Expression, comptime Args: type, comptime Captures: type) type {
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return switch (expression) {
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.arg_deref => |names| Deref(Args, names),
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.capture_deref => |names| Deref(Captures, names),
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};
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}
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fn evaluateExpression(
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comptime expression: Expression,
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args: anytype,
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captures: anytype,
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) EvaluateExpression(expression, @TypeOf(args), @TypeOf(captures)) {
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return switch (expression) {
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.arg_deref => |names| deref(args, names),
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.capture_deref => |names| deref(captures, names),
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};
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}
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fn AddCapture(comptime Root: type, comptime name: []const u8, comptime Val: type) type {
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var fields = std.meta.fields(Root) ++ [_]std.builtin.Type.StructField{.{
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.name = name,
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.field_type = Val,
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.default_value = null,
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.is_comptime = false,
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.alignment = @alignOf(Val),
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}};
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return @Type(.{ .Struct = .{
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.layout = .Auto,
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.fields = fields,
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.decls = &.{},
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.is_tuple = false,
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} });
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}
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fn addCapture(root: anytype, comptime name: []const u8, val: anytype) AddCapture(@TypeOf(root), name, @TypeOf(val)) {
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var result = std.mem.zeroInit(AddCapture(@TypeOf(root), name, @TypeOf(val)), root);
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@field(result, name) = val;
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return result;
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}
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const TemplateType = enum {
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root,
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for_block,
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if_block,
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};
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fn parseTemplate(
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comptime tokens: []const TemplateToken,
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comptime start: usize,
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comptime template_type: TemplateType,
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) ParseResult(usize, []const TemplateItem) {
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comptime {
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var i: usize = start;
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var current_text: []const u8 = "";
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var items: []const TemplateItem = &.{};
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while (i < tokens.len) : (i += 1) {
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switch (tokens[i]) {
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.text => |text| current_text = current_text ++ text,
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.whitespace => |wsp| {
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if (i != tokens.len - 1 and tokens[i + 1] == .control_block)
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if (tokens[i + 1].control_block.strip_before)
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continue;
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current_text = current_text ++ wsp;
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},
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.control_block => |cb| {
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if (current_text.len != 0) {
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items = items ++ [_]TemplateItem{.{ .text = current_text }};
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current_text = "";
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}
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switch (cb.block) {
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.expression => |expr| items = items ++ [_]TemplateItem{.{ .statement = .{ .expression = expr } }},
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.if_header => |header| {
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if (i != tokens.len - 1 and tokens[i + 1] == .whitespace and cb.strip_after) i += 1;
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const subtemplate = parseTemplate(tokens, i + 1, .if_block);
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items = items ++ [_]TemplateItem{.{
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.statement = .{
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.@"if" = .{
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.subtemplate = subtemplate.item,
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.header = header,
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},
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},
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}};
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i = subtemplate.new_iter;
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},
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.for_header => |header| {
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if (i != tokens.len - 1 and tokens[i + 1] == .whitespace and cb.strip_after) i += 1;
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const subtemplate = parseTemplate(tokens, i + 1, .for_block);
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items = items ++ [_]TemplateItem{.{
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.statement = .{
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.@"for" = .{
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.subtemplate = subtemplate.item,
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.header = header,
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},
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},
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}};
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i = subtemplate.new_iter;
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},
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.end_for => if (template_type == .for_block)
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break
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else
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@compileError("Unexpected /for tag"),
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.end_if => if (template_type == .if_block)
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break
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else
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@compileError("Unexpected /if tag"),
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}
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if (i != tokens.len - 1 and tokens[i] == .control_block) {
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if (tokens[i].control_block.strip_after and tokens[i + 1] == .whitespace) {
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i += 1;
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}
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}
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},
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}
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} else if (template_type != .root) @compileError("End tag not found");
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if (current_text.len != 0) items = items ++ [_]TemplateItem{.{ .text = current_text }};
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return .{
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.new_iter = i,
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.item = items,
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};
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}
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}
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const TemplateToken = union(enum) {
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text: []const u8,
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whitespace: []const u8,
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control_block: ControlBlock,
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};
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fn parseTemplateTokens(comptime tokens: ControlTokenIter) []const TemplateToken {
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comptime {
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var iter = tokens;
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var items: []const TemplateToken = &.{};
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while (iter.next()) |token| switch (token) {
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.whitespace => |wsp| items = items ++ [_]TemplateToken{.{ .whitespace = wsp }},
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.text => |text| items = items ++ [_]TemplateToken{.{ .text = text }},
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.open_bracket => {
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const next = iter.next() orelse @compileError("Unexpected end of template");
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if (next == .open_bracket) {
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items = items ++ [_]TemplateToken{.{ .text = "{" }};
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} else {
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iter.putBack(next);
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const result = parseControlBlock(iter);
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iter = result.new_iter;
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items = items ++ [_]TemplateToken{.{ .control_block = result.item }};
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}
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},
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.close_bracket => {
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const next = iter.next() orelse @compileError("Unexpected end of template");
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if (next == .close_bracket)
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items = items ++ [_]TemplateToken{.{ .text = "}" }}
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else
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@compileError("Unpaired close bracket, did you mean \"}}\"?");
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},
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.period => items = items ++ [_]TemplateToken{.{ .text = "." }},
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.pound => items = items ++ [_]TemplateToken{.{ .text = "#" }},
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.pipe => items = items ++ [_]TemplateToken{.{ .text = "|" }},
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.dollar => items = items ++ [_]TemplateToken{.{ .text = "$" }},
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.slash => items = items ++ [_]TemplateToken{.{ .text = "/" }},
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.equals => items = items ++ [_]TemplateToken{.{ .text = "=" }},
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};
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return items;
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}
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}
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fn parseExpression(comptime tokens: ControlTokenIter) ParseResult(ControlTokenIter, Expression) {
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comptime {
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var iter = tokens;
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var expr: Expression = while (iter.next()) |token| switch (token) {
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.whitespace => {},
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.period => {
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const names = parseDeref(iter);
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iter = names.new_iter;
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break .{ .arg_deref = names.item };
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},
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.dollar => {
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const names = parseDeref(iter);
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iter = names.new_iter;
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break .{ .capture_deref = names.item };
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},
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else => @compileError("TODO"),
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};
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return .{
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.new_iter = iter,
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.item = expr,
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};
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}
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}
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fn parseControlBlock(comptime tokens: ControlTokenIter) ParseResult(ControlTokenIter, ControlBlock) {
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comptime {
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var iter = tokens;
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const strip_before = if (iter.next()) |first| blk: {
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if (first == .equals) {
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break :blk true;
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}
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iter.putBack(first);
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break :blk false;
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} else @compileError("Unexpected end of template");
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var stmt: ControlBlock.Data = while (iter.next()) |token| switch (token) {
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.equals => @compileError("Unexpected '='"),
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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 (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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switch (keyword) {
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.@"for" => {
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const result = parseForHeader(iter);
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iter = result.new_iter;
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break .{ .for_header = result.item };
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},
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.@"if" => {
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const result = parseIfHeader(iter);
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iter = result.new_iter;
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break .{ .if_header = result.item };
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},
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//else => @compileError("TODO"),
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}
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},
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.slash => {
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const next = iter.next() orelse @compileError("Unexpected end of template");
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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(EndKeyword, text) orelse @compileError("Unknown keyword: " ++ text);
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switch (keyword) {
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.@"for" => break .{ .end_for = {} },
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.@"if" => break .{ .end_if = {} },
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}
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},
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.period, .dollar => {
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iter.putBack(token);
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const expr = parseExpression(iter);
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iter = expr.new_iter;
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break .{ .expression = expr.item };
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},
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else => @compileError("TODO"),
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};
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// search for end of statement
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var strip_after: bool = false;
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while (iter.next()) |token| switch (token) {
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.whitespace => {},
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.equals => {
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if (iter.peek()) |t| {
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if (t == .close_bracket) {
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strip_after = true;
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continue;
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}
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}
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@compileError("Unexpected '='");
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},
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.close_bracket => return .{
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.new_iter = iter,
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.item = .{
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.block = stmt,
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.strip_before = strip_before,
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.strip_after = strip_after,
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},
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},
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else => {
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@compileLog(iter.row);
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@compileError("TODO" ++ @tagName(token));
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},
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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 skipWhitespace(comptime tokens: ControlTokenIter) ControlTokenIter {
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comptime {
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var iter = tokens;
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while (iter.peek()) |token| switch (token) {
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.whitespace => _ = iter.next(),
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else => break,
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};
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return iter;
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}
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}
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fn endControlBlock(comptime tokens: ControlTokenIter) ControlTokenIter {
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comptime {
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var iter = skipWhitespace(tokens);
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const token = iter.next() orelse @compileError("Unexpected end of template");
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if (token != .close_bracket) @compileError("Unexpected token");
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return iter;
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}
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}
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fn parseForHeader(comptime tokens: ControlTokenIter) ParseResult(ControlTokenIter, ForHeader) {
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comptime {
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const iterable = parseExpression(tokens);
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var iter = iterable.new_iter;
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iter = skipWhitespace(iter);
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{
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const token = iter.next() orelse @compileError("Unexpected end of template");
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if (token != .pipe) @compileError("Unexpected token");
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}
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{
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const token = iter.next() orelse @compileError("Unexpected end of template");
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if (token != .dollar) @compileError("Unexpected token");
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}
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const capture = blk: {
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const token = iter.next() orelse @compileError("Unexpected end of template");
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if (token != .text) @compileError("Unexpected token");
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break :blk token.text;
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};
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{
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const token = iter.next() orelse @compileError("Unexpected end of template");
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if (token != .pipe) @compileError("Unexpected token");
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}
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return .{
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.new_iter = iter,
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.item = .{
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.iterable = iterable.item,
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.capture = capture,
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},
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};
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}
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}
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fn parseIfHeader(comptime tokens: ControlTokenIter) ParseResult(ControlTokenIter, IfHeader) {
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comptime {
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const condition = parseExpression(tokens);
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var iter = condition.new_iter;
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return .{
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.new_iter = iter,
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.item = .{
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.condition = condition.item,
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},
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};
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}
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}
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|
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fn parseDeref(comptime tokens: ControlTokenIter) ParseResult(ControlTokenIter, []const []const u8) {
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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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|
.item = 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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fn ParseResult(comptime It: type, comptime T: type) type {
|
|
return struct {
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|
new_iter: It,
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|
item: T,
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|
};
|
|
}
|
|
|
|
const TemplateItem = union(enum) {
|
|
text: []const u8,
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|
statement: Statement,
|
|
};
|
|
|
|
const Expression = union(enum) {
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|
arg_deref: []const []const u8,
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|
capture_deref: []const []const u8,
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};
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|
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const For = struct {
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|
subtemplate: []const TemplateItem,
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header: ForHeader,
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};
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|
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const ForHeader = struct {
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iterable: Expression,
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|
capture: []const u8,
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};
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|
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const If = struct {
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|
subtemplate: []const TemplateItem,
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|
header: IfHeader,
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};
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|
|
|
const IfHeader = struct {
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condition: Expression,
|
|
};
|
|
|
|
const Statement = union(enum) {
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|
expression: Expression,
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|
@"for": For,
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|
@"if": If,
|
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};
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|
|
|
const ControlBlock = struct {
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|
const Data = union(enum) {
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expression: Expression,
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|
for_header: ForHeader,
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|
end_for: void,
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|
if_header: IfHeader,
|
|
end_if: void,
|
|
};
|
|
block: Data,
|
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strip_before: bool,
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|
strip_after: bool,
|
|
};
|
|
|
|
const Keyword = enum {
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|
@"for",
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|
@"if",
|
|
};
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|
|
|
const EndKeyword = enum {
|
|
@"for",
|
|
@"if",
|
|
};
|
|
|
|
const ControlToken = union(enum) {
|
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text: []const u8,
|
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open_bracket: void,
|
|
close_bracket: void,
|
|
period: void,
|
|
whitespace: []const u8,
|
|
pound: void,
|
|
pipe: void,
|
|
dollar: void,
|
|
slash: void,
|
|
equals: void,
|
|
};
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|
|
|
const ControlTokenIter = struct {
|
|
start: usize = 0,
|
|
text: []const u8,
|
|
peeked_token: ?ControlToken = null,
|
|
|
|
row: usize = 0,
|
|
|
|
fn next(self: *ControlTokenIter) ?ControlToken {
|
|
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 = {} },
|
|
'#' => return .{ .pound = {} },
|
|
'|' => return .{ .pipe = {} },
|
|
'$' => return .{ .dollar = {} },
|
|
'/' => return .{ .slash = {} },
|
|
'=' => return .{ .equals = {} },
|
|
' ', '\t', '\n', '\r' => {
|
|
var idx: usize = 0;
|
|
while (idx < remaining.len and std.mem.indexOfScalar(u8, " \t\n\r", remaining[idx]) != null) : (idx += 1) {}
|
|
const newline_count = std.mem.count(u8, remaining[0..idx], "\n");
|
|
self.row += newline_count;
|
|
|
|
self.start += idx - 1;
|
|
return .{ .whitespace = remaining[0..idx] };
|
|
},
|
|
else => {
|
|
var idx: usize = 0;
|
|
while (idx < remaining.len and std.mem.indexOfScalar(u8, "{}.#|$/= \t\n\r", remaining[idx]) == null) : (idx += 1) {}
|
|
|
|
self.start += idx - 1;
|
|
return .{ .text = remaining[0..idx] };
|
|
},
|
|
}
|
|
}
|
|
|
|
fn peek(self: *ControlTokenIter) ?ControlToken {
|
|
const token = self.next();
|
|
self.peeked_token = token;
|
|
return token;
|
|
}
|
|
|
|
fn putBack(self: *ControlTokenIter, token: ControlToken) void {
|
|
std.debug.assert(self.peeked_token == null);
|
|
self.peeked_token = token;
|
|
}
|
|
};
|
|
|
|
test "template" {
|
|
const testCase = struct {
|
|
fn case(comptime tmpl: []const u8, args: anytype, expected: []const u8) !void {
|
|
var stream = std.io.changeDetectionStream(expected, std.io.null_writer);
|
|
try execute(stream.writer(), tmpl, args);
|
|
try std.testing.expect(!stream.changeDetected());
|
|
}
|
|
}.case;
|
|
|
|
try testCase("", .{}, "");
|
|
try testCase("abcd", .{}, "abcd");
|
|
try testCase("{.val}", .{ .val = 3 }, "3");
|
|
try testCase("{#if .val}1{/if}", .{ .val = true }, "1");
|
|
try testCase("{#for .vals |$v|}{$v}{/for}", .{ .vals = [_]u8{ 1, 2, 3 } }, "123");
|
|
try testCase("{#for .vals |$v|=} {$v} {=/for}", .{ .vals = [_]u8{ 1, 2, 3 } }, "123");
|
|
}
|