feat: Warns the user if they exceed 16 context frames.

TODOS.md

@@ -2,18 +2,25 @@
 
 - Polish existing features before moving on to new ones.
 - [ ] Improve diagnostics
+  - [ ] show "stack traces" in template error diagnostics
+  - [ ] better diagnostics for syntax errors in treesitter.
+  - [ ] Ensure diagnostics for MAX_CONTEXT_DEPTH are good.
+  - [ ] show a proper diagnostic for timezones
+    - currently "unable to load timezone 'America/New_Yorkskie'"
+    - want rust style diagnostic and better message, maybe "unknown timezone 'America/New_Yorkskie'"
 - [x] Simplify / unify template context stack. Come up with a name for it.
   - [x] `render_template` should accept `Template_Context`, not `any`
 - [ ] Load grammars dynamically
-- [ ] consider adding a limit to the context stack in mustache.
+- [x] consider adding a limit to the context stack in mustache.
-- [ ] better diagnostics for syntax errors in treesitter.
 - [x] Add heading ids as a default on extension.
-- [ ] show "stack traces" in template error diagnostics
 - [ ] starred must be a param.
-- [ ] Add a `#config(MAX_CONTEXT_DEPTH, 16?)` to `mustache`.
+- [x] Add a `#config(MAX_CONTEXT_DEPTH, 16?)` to `mustache`.
+- [ ] Documentation
+  - [ ] talk about the context stack (and its limit).
 - [ ] menu system
   - [ ] like Hugo's, but warn(/fail?) if menus are defined in the config *and* pages.
     - i.e. force the user to choose one or the other.
+- [ ] Don't show annoying log output in tests.
 
 ## Performance
 
@@ -69,9 +76,6 @@
 - [ ] display an error when no part of the date appears in the output.
 - [ ] Handle 0 and whitespace padding i.e. "_2" -> " 2"
 - [ ] Do we *need* mustache.Date_Components, or can we use core:time/datetime.DateTime?
-- [ ] show a proper diagnostic for timezones
-  - currently "unable to load timezone 'America/New_Yorkskie'"
-  - want rust style diagnostic and better message, maybe "unknown timezone 'America/New_Yorkskie'"
 
 ## General 
 - [ ] get rid of the global variables in the `treesitter` package.

mustache/mustache.odin

@@ -3,9 +3,19 @@ package mustache
 import "base:runtime"
 import "core:fmt"
 import "core:log"
-import "core:reflect"
 import "core:strings"
 
+// A hypothetical maximum context depth. Trying to pass more than this many items
+// to render(tpl, data), or nesting templates further than this depth would be
+// an error.
+// May be enforced in a later version (for performance)
+MAX_CONTEXT_DEPTH :: #config(MAX_CONTEXT_DEPTH, 16)
+
+// Context_Stack is the growable stack of data frames walked top-to-bottom by
+// resolve_name. Frames are pushed on section descent and popped on exit; the
+// root data (or each element of a root []any) forms the base frames.
+Context_Stack :: [dynamic]any
+
 // ---------------------------------------------------------------------------
 // Error types
 // ---------------------------------------------------------------------------
@@ -22,14 +32,18 @@ Error_Body :: struct {
 }
 
 // Error is nil when no error occurred.
-Error :: union { Error_Body }
+Error :: union {
+	Error_Body,
+}
 
 // body unwraps the Error_Body from a non-nil Error.
 // Precondition: err != nil.
 body :: proc(err: Error) -> Error_Body {
 	switch e in err {
-	case Error_Body: return e
+	case Error_Body:
-	case: return {}
+		return e
+	case:
+		return {}
 	}
 }
 
@@ -143,11 +157,9 @@ render :: proc(
 	err: Error,
 ) {
 	builder: strings.Builder
-	strings.builder_init(&builder, allocator)
+	strings.builder_init(&builder, context.temp_allocator)
-	defer strings.builder_destroy(&builder)
 
-	ctx := make([dynamic]any, 0, 4, allocator)
+	ctx := make(Context_Stack, 0, 4, context.temp_allocator)
-	defer delete(ctx)
 
 	// If data is a []any, expand into individual context frames.
 	// Otherwise, push as a single frame.
@@ -331,12 +343,7 @@ parse_section :: proc(
 			idx := len(nodes)
 			append(
 				nodes,
-				Node {
+				Node{kind = .Parent, key = tok.value, indent = tok.indent, pos = tok.pos},
-					kind = .Parent,
-					key = tok.value,
-					indent = tok.indent,
-					pos = tok.pos,
-				},
 			)
 			parse_section(tokens, pos, nodes, tok.value, source, allocator, tok.pos) or_return
 			nodes[idx].children = nodes[idx + 1:len(nodes)]
@@ -344,15 +351,7 @@ parse_section :: proc(
 		case .Block_Open:
 			pos^ += 1
 			idx := len(nodes)
-			append(
+			append(nodes, Node{kind = .Block, key = tok.value, indent = tok.indent, pos = tok.pos})
-				nodes,
-				Node {
-					kind = .Block,
-					key = tok.value,
-					indent = tok.indent,
-					pos = tok.pos,
-				},
-			)
 			parse_section(tokens, pos, nodes, tok.value, source, allocator, tok.pos) or_return
 			nodes[idx].children = nodes[idx + 1:len(nodes)]
 		}
@@ -499,21 +498,29 @@ remove_line_indent :: proc(s: string, indent: string, allocator := context.alloc
 
 render_template :: proc(
 	pt: Template,
-	ctx: ^[dynamic]any,
+	ctx: ^Context_Stack,
 	partials: map[string]Template,
 	b: ^strings.Builder,
 	blocks: map[string]Block_Override,
 	indent: string,
 ) -> Error {
 	if len(indent) > 0 {
-		state := Indent_State{indent = indent, at_line_start = false}
+		state := Indent_State {
+			indent        = indent,
+			at_line_start = false,
+		}
 		strings.write_string(b, indent) // first line always gets indent
 		return render_nodes(pt, pt.nodes[:], ctx, partials, b, blocks, &state)
 	}
 	return render_nodes(pt, pt.nodes[:], ctx, partials, b, blocks, nil)
 }
 
-write_indented :: proc(b: ^strings.Builder, indent: string, content: string, at_line_start: ^bool) {
+write_indented :: proc(
+	b: ^strings.Builder,
+	indent: string,
+	content: string,
+	at_line_start: ^bool,
+) {
 	if len(indent) == 0 || len(content) == 0 {
 		strings.write_string(b, content)
 		return
@@ -544,7 +551,7 @@ write_indented :: proc(b: ^strings.Builder, indent: string, content: string, at_
 render_nodes :: proc(
 	current: Template,
 	nodes: []Node,
-	ctx: ^[dynamic]any,
+	ctx: ^Context_Stack,
 	partials: map[string]Template,
 	b: ^strings.Builder,
 	blocks: map[string]Block_Override = nil,
@@ -682,7 +689,7 @@ render_nodes :: proc(
 				if elem_info != nil {
 					for j in 0 ..< count {
 						elem := extract_list_element(elem_info, data, j)
-					append(ctx, elem)
+						context_push(ctx, elem, current, node)
 						defer pop(ctx)
 						render_nodes(
 							current,
@@ -695,9 +702,17 @@ render_nodes :: proc(
 						) or_return
 					}
 				} else {
-				append(ctx, val)
+					context_push(ctx, val, current, node)
 					defer pop(ctx)
-				render_nodes(current, children, ctx, partials, b, blocks, indent_state) or_return
+					render_nodes(
+						current,
+						children,
+						ctx,
+						partials,
+						b,
+						blocks,
+						indent_state,
+					) or_return
 				}
 			}
 			i += 1 + len(node.children)
@@ -715,7 +730,15 @@ render_nodes :: proc(
 				val = transformed
 			}
 			if !is_truthy(val) {
-			render_nodes(current, node.children, ctx, partials, b, blocks, indent_state) or_return
+				render_nodes(
+					current,
+					node.children,
+					ctx,
+					partials,
+					b,
+					blocks,
+					indent_state,
+				) or_return
 			}
 			i += 1 + len(node.children)
 
@@ -937,3 +960,25 @@ warn_unmatched_block_overrides :: proc(
 	}
 }
 
+context_push :: proc(ctx: ^Context_Stack, val: any, current: Template, node: Node) {
+	append(ctx, val)
+	if len(ctx^) == MAX_CONTEXT_DEPTH + 1 {
+		warn_context_depth(current, node)
+	}
+}
+
+// warn_context_depth emits a diagnostic warning pointing at the section tag
+// whose push carried the context stack past MAX_CONTEXT_DEPTH.
+warn_context_depth :: proc(current: Template, node: Node) {
+	msg := fmt.tprintf(
+		"context stack depth exceeded %d (possible recursive section/partial)",
+		MAX_CONTEXT_DEPTH,
+	)
+	path := current.path
+	if path == "" {
+		path = "<input>"
+	}
+	diag := format_error(path, current.source, node.pos, msg, "", colorize = should_colorize())
+	log.warnf("%s", diag)
+}
+

mustache/mustache_test.odin

@@ -1,7 +1,9 @@
 #+test
 package mustache
 
+import "core:log"
 import "core:mem"
+import "core:strings"
 import "core:testing"
 
 @(test)
@@ -124,3 +126,39 @@ leak_repeated_render :: proc(t: ^testing.T) {
 	}
 }
 
+// A deeply nested map pushes the context stack past MAX_CONTEXT_DEPTH (16).
+// The depth warning must be non-fatal: rendering still succeeds.
+@(test)
+test_context_depth_warns :: proc(t: ^testing.T) {
+	context.logger = log.nil_logger()
+
+	AMT :: MAX_CONTEXT_DEPTH + 2
+
+	// Build AMT nested {x: {...}} levels; the innermost holds `leaf`.
+	data := make(map[string]any, context.temp_allocator)
+	data["leaf"] = "found"
+	for _ in 0 ..< AMT {
+		outer := make(map[string]any, context.temp_allocator)
+		outer["x"] = data
+		data = outer
+	}
+
+	// Template: AMT nested {{#x}} sections around {{leaf}}.
+	src: strings.Builder
+	strings.builder_init(&src, context.temp_allocator)
+	for _ in 0 ..< AMT do strings.write_string(&src, "{{#x}}")
+	strings.write_string(&src, "{{leaf}}")
+	for _ in 0 ..< AMT do strings.write_string(&src, "{{/x}}")
+	template := strings.to_string(src)
+
+	tmpl, perr := parse(template, "<depth-test>", context.temp_allocator)
+	testing.expect(t, perr == nil, "should parse")
+	if perr != nil {
+		return
+	}
+
+	result, rerr := render(tmpl, data, allocator = context.temp_allocator)
+	testing.expect(t, rerr == nil, "depth warning must be non-fatal")
+	testing.expect_value(t, result, "found")
+}
+

mustache/suggest.odin

@@ -153,10 +153,7 @@ suggest_correction :: proc(available: []string, missing: string) -> string {
 	if len(available) == 0 || len(missing) == 0 {
 		return ""
 	}
-	threshold := 2
+	threshold := max(2, len(missing) / 3)
-	if len(missing) > 8 {
-		threshold = len(missing) / 4
-	}
 
 	best: string
 	best_dist := threshold + 1

mustache/suggest_test.odin

@@ -10,9 +10,13 @@ Inner :: struct {
 	bar: int,
 }
 
+Page :: struct {
+	title: string,
+}
+
 Outer :: struct {
 	title:   string,
-	page.title: string,
+	page:    Page,
 	inner:   Inner,
 	numbers: [3]int,
 }