From 9d74bce266090fc3f5caa954adb44c62c8163be5 Mon Sep 17 00:00:00 2001
From: jaina heartles <me@heartles.xyz>
Date: Tue, 15 Nov 2022 23:53:29 -0800
Subject: [PATCH] Add loop captures

---
 src/template/lib.zig       | 72 ++++++++++++++++++++++++++++----------
 src/template/test.tmp.html |  3 +-
 2 files changed, 55 insertions(+), 20 deletions(-)

diff --git a/src/template/lib.zig b/src/template/lib.zig
index 3e014e5..07a93b5 100644
--- a/src/template/lib.zig
+++ b/src/template/lib.zig
@@ -33,8 +33,10 @@ fn executeStatement(writer: anytype, comptime stmt: Statement, args: anytype) !v
         .for_loop => |loop| {
             const fields = loop.iterable.arg_deref;
             const iterable = argDeref(args, fields);
-            for (iterable) |str| {
-                try writer.writeAll(str);
+            const subtemplate = loop.subtemplate;
+            try writer.writeAll("capture on " ++ loop.capture ++ ": ");
+            for (iterable) |_| {
+                try executeTemplate(writer, subtemplate, args);
             }
         },
         else => @compileError("TODO"),
@@ -102,6 +104,8 @@ fn parseTemplate(comptime tokens: TokenIter, comptime template_type: TemplateTyp
                 },
                 .period => current_text = current_text ++ ".",
                 .pound => current_text = current_text ++ "#",
+                .pipe => current_text = current_text ++ "|",
+                .dollar => current_text = current_text ++ "$",
             }
         }
 
@@ -166,22 +170,56 @@ fn parseStatement(comptime tokens: TokenIter) ParseResult(Statement) {
     }
 }
 
+fn skipWhitespace(comptime tokens: TokenIter) TokenIter {
+    comptime {
+        var iter = tokens;
+        while (iter.peek()) |token| switch (token) {
+            .whitespace => _ = iter.next(),
+            else => break,
+        };
+
+        return iter;
+    }
+}
+
+fn endStatement(comptime tokens: TokenIter) TokenIter {
+    comptime {
+        var iter = skipWhitespace(tokens);
+
+        const token = iter.next() orelse @compileError("Unexpected end of template");
+        if (token != .close_bracket) @compileError("Unexpected token");
+        return iter;
+    }
+}
+
 fn parseForLoop(comptime tokens: TokenIter) ParseResult(ForLoop) {
     comptime {
         const iterable = parseExpression(tokens);
         var iter = iterable.new_iter;
-        while (iter.next()) |token| switch (token) {
-            .whitespace => {},
-            .close_bracket => break,
-            else => @compileError("Unexpected token"),
+
+        iter = skipWhitespace(iter);
+        {
+            const token = iter.next() orelse @compileError("Unexpected end of template");
+            if (token != .pipe) @compileError("Unexpected token");
+        }
+        {
+            const token = iter.next() orelse @compileError("Unexpected end of template");
+            if (token != .dollar) @compileError("Unexpected token");
+        }
+        const capture = blk: {
+            const token = iter.next() orelse @compileError("Unexpected end of template");
+            if (token != .text) @compileError("Unexpected token");
+            break :blk token.text;
         };
+        {
+            const token = iter.next() orelse @compileError("Unexpected end of template");
+            if (token != .pipe) @compileError("Unexpected token");
+        }
+        iter = endStatement(iter);
 
         const subtemplate = parseTemplate(iter, .subtemplate);
 
-        return .{ .new_iter = subtemplate.new_iter, .item = .{
-            .iterable = iterable.item,
-            .subtemplate = subtemplate.item,
-        } };
+        return .{ .new_iter = subtemplate.new_iter, .item = .{ .iterable = iterable.item, .subtemplate = subtemplate.item, .capture = capture } };
     }
 }
 
@@ -247,6 +285,7 @@ const Expression = union(enum) {
 const ForLoop = struct {
     subtemplate: []const TemplateItem,
     iterable: Expression,
+    capture: []const u8,
 };
 
 const Statement = union(enum) {
@@ -255,13 +294,6 @@ const Statement = union(enum) {
     end_for: void,
 };
 
-const State = enum {
-    text,
-    text_close_bracket,
-    template_start,
-    template,
-};
-
 const Keyword = enum {
     @"for",
     end_for,
@@ -274,6 +306,8 @@ const Token = union(enum) {
     period: void,
     whitespace: []const u8,
     pound: void,
+    pipe: void,
+    dollar: void,
 };
 
 const TokenIter = struct {
@@ -299,6 +333,8 @@ const TokenIter = struct {
             '}' => return .{ .close_bracket = {} },
             '.' => return .{ .period = {} },
             '#' => return .{ .pound = {} },
+            '|' => return .{ .pipe = {} },
+            '$' => return .{ .dollar = {} },
             ' ', '\t', '\n', '\r' => {
                 var idx: usize = 0;
                 while (idx < remaining.len and std.mem.indexOfScalar(u8, " \t\n\r", remaining[idx]) != null) : (idx += 1) {}
@@ -310,7 +346,7 @@ const TokenIter = struct {
             },
             else => {
                 var idx: usize = 0;
-                while (idx < remaining.len and std.mem.indexOfScalar(u8, "{}.# \t\n\r", remaining[idx]) == null) : (idx += 1) {}
+                while (idx < remaining.len and std.mem.indexOfScalar(u8, "{}.#|$ \t\n\r", remaining[idx]) == null) : (idx += 1) {}
 
                 self.start += idx - 1;
                 return .{ .text = remaining[0..idx] };
diff --git a/src/template/test.tmp.html b/src/template/test.tmp.html
index c00d1c4..2f39f2a 100644
--- a/src/template/test.tmp.html
+++ b/src/template/test.tmp.html
@@ -9,8 +9,7 @@
     <h2> {{ REAL BRACKETS }} </h2>
 
     <section>
-      {#for .foo}
-      {#end_for}
+      {#for .foo |$f|}a testing thing {#end_for}
       {{#for args.notes |$note, $i|}}
         <h3>Note no. {{$i}}</h3>
         {{#template note_display ($note)}}