From 250e56a7821a3c6db9453ded696f9f3c622c94b0 Mon Sep 17 00:00:00 2001
From: Meghan Denny <hello@nektro.net>
Date: Fri, 6 Aug 2021 02:20:25 -0700
Subject: [PATCH] add functions and the `#each` helper

---
 src/astgen.zig | 38 ++++++++++++++++++++++++++++++++++++++
 src/lib.zig    | 19 ++++++++++++++++++-
 src/main.zig   | 14 ++++++++++++++
 3 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/src/astgen.zig b/src/astgen.zig
index 860fff764a8fa026af7e5e51c47ddcbc768c53ad..08df3cbde58a7103c81ba66ae130816bb3e10aa6 100644
--- a/src/astgen.zig
+++ b/src/astgen.zig
@@ -11,6 +11,8 @@ pub const Value = union(enum) {
     attr: Attr,
     string: string,
     replacement: []const string,
+    block: Block,
+    function: Fn,
 };
 
 pub const Element = struct {
@@ -24,6 +26,21 @@ pub const Attr = struct {
     value: string,
 };
 
+pub const Block = struct {
+    name: Type,
+    args: []const string,
+    body: []const Value,
+
+    pub const Type = enum {
+        each,
+    };
+};
+
+pub const Fn = struct {
+    name: string,
+    args: []const string,
+};
+
 //
 //
 
@@ -107,6 +124,27 @@ const Parser = struct {
             return Value{ .string = self.eat(.string) };
         }
         if (self.tryEatSymbol("{")) {
+            if (self.tryEatSymbol("#")) {
+                const w = self.eat(.word);
+                if (std.meta.stringToEnum(Block.Type, w)) |name| {
+                    const args = self.doReplacement();
+                    var children: []const Value = &.{};
+                    while (!self.tryEatSymbol("/")) {
+                        children = children ++ &[_]Value{self.doValue()};
+                    }
+                    std.debug.assert(std.mem.eql(u8, @tagName(name), self.eat(.word)));
+                    self.eatSymbol("/");
+                    return Value{ .block = Block{
+                        .name = name,
+                        .args = args,
+                        .body = children,
+                    } };
+                }
+                return Value{ .function = .{
+                    .name = w,
+                    .args = self.doReplacement(),
+                } };
+            }
             return Value{ .replacement = self.doReplacement() };
         }
         return Value{ .element = self.doElement() };
diff --git a/src/lib.zig b/src/lib.zig
index 5c7e9212e584aecee04ee357fa99812c10a8430f..1e7dfaf83724ac4e1b1a13815fe9cd3a99b3cbf0 100644
--- a/src/lib.zig
+++ b/src/lib.zig
@@ -29,7 +29,7 @@ const tokenize = @import("./tokenize.zig");
 const astgen = @import("./astgen.zig");
 
 pub fn parse(comptime input: []const u8) astgen.Value {
-    return astgen.Value{ .element = astgen.do(tokenize.do(input, &.{ '[', '=', ']', '(', ')', '{', '}' })) };
+    return astgen.Value{ .element = astgen.do(tokenize.do(input, &.{ '[', '=', ']', '(', ')', '{', '}', '#', '/' })) };
 }
 
 pub fn compile(writer: anytype, comptime value: astgen.Value, data: anytype) !void {
@@ -82,6 +82,23 @@ fn do(writer: anytype, comptime value: astgen.Value, data: anytype, indent: usiz
                 try do(writer, astgen.Value{ .replacement = v[1..] }, x, indent, flag1);
             }
         },
+        .block => |v| {
+            const x = comptime search(data, v.args);
+
+            switch (v.name) {
+                .each => {
+                    inline for (x) |item| {
+                        inline for (v.body) |val| {
+                            try do(writer, val, item, indent, flag1);
+                        }
+                    }
+                },
+            }
+        },
         else => unreachable,
     }
 }
+
+fn search(comptime T: anytype, comptime args: []const []const u8) @TypeOf(if (args.len == 1) @field(T, args[0]) else search(@TypeOf(@field(T, args[0])), args[1..])) {
+    return if (args.len == 1) @field(T, args[0]) else search(@TypeOf(@field(T, args[0])), args[1..]);
+}
diff --git a/src/main.zig b/src/main.zig
index 6633f47575df93debc4b8141ea44bfb1c43e0038..195310400e78bae2c16f3ae0135d63cea05fede1 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -14,6 +14,13 @@ const example_document =
     \\        p("This is an example HTML document written in "a[href="https://github.com/nektro/zig-pek"]("Pek")".")
     \\        p("Pek is written by "{author}".")
     \\        p("Her favorite plant is the "{favorite flower})
+    \\        br
+    \\        p("The most populous US cities are:")
+    \\        ul(
+    \\            {#each top_cities}
+    \\            li({name})
+    \\            /each/
+    \\        )
     \\    )
     \\)
 ;
@@ -28,6 +35,13 @@ pub fn main() !void {
         .favorite = .{
             .flower = "Sunflower",
         },
+        .top_cities = .{
+            .{ .name = "New York" },
+            .{ .name = "Los Angeles" },
+            .{ .name = "Chicago" },
+            .{ .name = "Houston" },
+            .{ .name = "Phoenix" },
+        },
     };
     try pek.compile(std.io.getStdErr().writer(), doc, data);
     std.debug.print("\n", .{});
-- 
2.54.0