feat: Optimize engine in javascript

Engine is no longer being compiled to a recursive function. Which means that we no longer depend on the JS engine doing tail call optimization correctly. Which it usually didn't.
Olian04 · Jul 10, 2024 · bda14e3 · bda14e3
1 parent 5a5f2e7
commit bda14e3
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Showing 6 changed files with 134 additions and 59 deletions.
diff --git a/src/handles.gleam b/src/handles.gleam
@@ -34,4 +34,5 @@ pub fn run(
     })
 
   engine.run(ast, ctx, partials_dict, string_builder.new())
+  |> result.map(string_builder.to_string)
 }
diff --git a/src/handles/internal/engine.gleam b/src/handles/internal/engine.gleam
@@ -1,37 +1,132 @@
-import gleam/bool
 import gleam/dict
-import gleam/result
+import gleam/list
 import gleam/string_builder
 import handles/ctx
 import handles/error
 import handles/internal/ctx_utils
 import handles/internal/parser
 
-fn run_each(
-  ctxs: List(ctx.Value),
-  ast: List(parser.AST),
-  builder: string_builder.StringBuilder,
-  partials: dict.Dict(String, List(parser.AST)),
-) -> Result(String, error.RuntimeError) {
-  case ctxs {
-    [] -> builder |> string_builder.to_string |> Ok
-    [ctx, ..rest] ->
-      run(ast, ctx, partials, string_builder.new())
-      |> result.try(fn(it) {
-        run_each(rest, ast, builder |> string_builder.append(it), partials)
-      })
-  }
+type Action {
+  Append(String)
+  SetCtx(ctx.Value)
+  Continue(List(parser.AST))
+  Stop(error.RuntimeError)
 }
 
-fn run_if(
-  bool: Bool,
-  children: List(parser.AST),
+pub fn eval(
+  actions: List(Action),
   ctx: ctx.Value,
   partials: dict.Dict(String, List(parser.AST)),
-) -> Result(String, error.RuntimeError) {
-  case bool {
-    False -> Ok("")
-    True -> run(children, ctx, partials, string_builder.new())
+  builder: string_builder.StringBuilder,
+) -> Result(string_builder.StringBuilder, error.RuntimeError) {
+  case actions {
+    [] -> Ok(builder)
+
+    [Stop(err)] -> Error(err)
+
+    [Stop(err), ..] -> Error(err)
+
+    [Append(value), ..rest_action] ->
+      eval(rest_action, ctx, partials, string_builder.append(builder, value))
+
+    [SetCtx(ctx), ..rest_action] -> eval(rest_action, ctx, partials, builder)
+
+    [Continue([]), ..rest_action] -> eval(rest_action, ctx, partials, builder)
+
+    [Continue([parser.Constant(_, value), ..rest_ast]), ..rest_action] ->
+      eval(
+        [Append(value), Continue(rest_ast), ..rest_action],
+        ctx,
+        partials,
+        builder,
+      )
+
+    [Continue([parser.Property(index, path), ..rest_ast]), ..rest_action] ->
+      case ctx_utils.get_property(path, ctx, index) {
+        Ok(str) ->
+          eval(
+            [Append(str), Continue(rest_ast), ..rest_action],
+            ctx,
+            partials,
+            builder,
+          )
+        Error(err) -> eval([Stop(err)], ctx, partials, builder)
+      }
+
+    [Continue([parser.Partial(index, id, path), ..rest_ast]), ..rest_action] ->
+      case dict.get(partials, id) {
+        Error(_) ->
+          eval([Stop(error.UnknownPartial(index, id))], ctx, partials, builder)
+        Ok(partial) ->
+          case ctx_utils.get(path, ctx, index) {
+            Error(err) -> eval([Stop(err)], ctx, partials, builder)
+            Ok(new_ctx) ->
+              eval(
+                [
+                  SetCtx(new_ctx),
+                  Continue(partial),
+                  SetCtx(ctx),
+                  Continue(rest_ast),
+                  ..rest_action
+                ],
+                ctx,
+                partials,
+                builder,
+              )
+          }
+      }
+    [
+      Continue([parser.IfBlock(index, path, children), ..rest_ast]),
+      ..rest_action
+    ] ->
+      case ctx_utils.get_bool(path, ctx, index) {
+        Error(err) -> eval([Stop(err)], ctx, partials, builder)
+        Ok(False) ->
+          eval([Continue(rest_ast), ..rest_action], ctx, partials, builder)
+        Ok(True) ->
+          eval(
+            [Continue(children), Continue(rest_ast), ..rest_action],
+            ctx,
+            partials,
+            builder,
+          )
+      }
+    [
+      Continue([parser.UnlessBlock(index, path, children), ..rest_ast]),
+      ..rest_action
+    ] ->
+      case ctx_utils.get_bool(path, ctx, index) {
+        Error(err) -> eval([Stop(err)], ctx, partials, builder)
+        Ok(True) ->
+          eval([Continue(rest_ast), ..rest_action], ctx, partials, builder)
+        Ok(False) ->
+          eval(
+            [Continue(children), Continue(rest_ast), ..rest_action],
+            ctx,
+            partials,
+            builder,
+          )
+      }
+    [
+      Continue([parser.EachBlock(index, path, children), ..rest_ast]),
+      ..rest_action
+    ] ->
+      case ctx_utils.get_list(path, ctx, index) {
+        Error(err) -> eval([Stop(err)], ctx, partials, builder)
+        Ok([]) ->
+          eval([Continue(rest_ast), ..rest_action], ctx, partials, builder)
+        Ok(ctxs) ->
+          eval(
+            ctxs
+              |> list.flat_map(fn(new_ctx) {
+                [SetCtx(new_ctx), Continue(children), SetCtx(ctx)]
+              })
+              |> list.append([Continue(rest_ast), ..rest_action]),
+            ctx,
+            partials,
+            builder,
+          )
+      }
   }
 }
 
@@ -40,40 +135,6 @@ pub fn run(
   ctx: ctx.Value,
   partials: dict.Dict(String, List(parser.AST)),
   builder: string_builder.StringBuilder,
-) -> Result(String, error.RuntimeError) {
-  case ast {
-    [] -> builder |> string_builder.to_string |> Ok
-    [node, ..rest] ->
-      case node {
-        parser.Constant(_, value) -> Ok(value)
-        parser.Property(index, path) -> ctx_utils.get_property(path, ctx, index)
-        parser.Partial(index, id, path) ->
-          case dict.get(partials, id) {
-            Error(_) -> Error(error.UnknownPartial(index, id))
-            Ok(partial) ->
-              ctx_utils.get(path, ctx, index)
-              |> result.try(run(partial, _, partials, string_builder.new()))
-          }
-
-        parser.IfBlock(index, path, children) ->
-          ctx_utils.get_bool(path, ctx, index)
-          |> result.try(run_if(_, children, ctx, partials))
-        parser.UnlessBlock(index, path, children) ->
-          ctx_utils.get_bool(path, ctx, index)
-          |> result.map(bool.negate)
-          |> result.try(run_if(_, children, ctx, partials))
-        parser.EachBlock(index, path, children) ->
-          ctx_utils.get_list(path, ctx, index)
-          |> result.try(run_each(_, children, string_builder.new(), partials))
-      }
-      |> result.try(fn(it) {
-        run(
-          rest,
-          ctx,
-          partials,
-          builder
-            |> string_builder.append(it),
-        )
-      })
-  }
+) -> Result(string_builder.StringBuilder, error.RuntimeError) {
+  eval([Continue(ast)], ctx, partials, builder)
 }
diff --git a/test/unit_tests/engine_test.gleam b/test/unit_tests/engine_test.gleam
@@ -9,6 +9,7 @@ pub fn hello_world_test() {
   [parser.Constant(0, "Hello World")]
   |> engine.run(ctx.Dict([]), dict.new(), string_builder.new())
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("Hello World")
 }
 
@@ -20,13 +21,15 @@ pub fn hello_name_test() {
     string_builder.new(),
   )
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("Hello Oliver")
 }
 
 pub fn self_tag_test() {
   [parser.Property(0, [])]
   |> engine.run(ctx.Str("Hello"), dict.new(), string_builder.new())
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("Hello")
 }
 
@@ -38,6 +41,7 @@ pub fn nested_property_test() {
     string_builder.new(),
   )
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("42")
 }
 
@@ -52,6 +56,7 @@ pub fn truthy_if_test() {
     string_builder.new(),
   )
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("42")
 }
 
@@ -63,6 +68,7 @@ pub fn falsy_if_test() {
     string_builder.new(),
   )
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("")
 }
 
@@ -74,6 +80,7 @@ pub fn truthy_unless_test() {
     string_builder.new(),
   )
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("")
 }
 
@@ -88,6 +95,7 @@ pub fn falsy_unless_test() {
     string_builder.new(),
   )
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("42")
 }
 
@@ -115,6 +123,7 @@ pub fn each_test() {
     string_builder.new(),
   )
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("They are Knatte, Fnatte, Tjatte, and Kalle")
 }
 
@@ -131,5 +140,6 @@ pub fn empty_each_test() {
     string_builder.new(),
   )
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal("")
 }
diff --git a/test/user_stories/hello_test.gleam b/test/user_stories/hello_test.gleam
@@ -36,5 +36,6 @@ pub fn parser_test() {
 pub fn engine_test() {
   engine.run(expected_ast, input_context, dict.new(), string_builder.new())
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal(expected_output)
 }
diff --git a/test/user_stories/knattarna_test.gleam b/test/user_stories/knattarna_test.gleam
@@ -55,5 +55,6 @@ pub fn parser_test() {
 pub fn engine_test() {
   engine.run(expected_ast, input_context, dict.new(), string_builder.new())
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal(expected_output)
 }
diff --git a/test/user_stories/nested_block_test.gleam b/test/user_stories/nested_block_test.gleam
@@ -76,5 +76,6 @@ pub fn parser_test() {
 pub fn engine_test() {
   engine.run(expected_ast, input_context, dict.new(), string_builder.new())
   |> should.be_ok
+  |> string_builder.to_string
   |> should.equal(expected_output)
 }
-Original file line number
+Diff line change
@@ Expand Up / @@ -34,4 +34,5 @@ pub fn run( @@
         })
       engine.run(ast, ctx, partials_dict, string_builder.new())
+      |> result.map(string_builder.to_string)
     }