tmpl: enforce stricter line checking for html interpolation (#11413)

vlib/v/parser/tmpl.v

@@ -193,16 +193,16 @@ mut sb := strings.new_builder($lstartlength)\n
 			pos := line.index('@for') or { continue }
 			source.writeln('for ' + line[pos + 4..] + '{')
 			source.writeln(parser.tmpl_str_start)
-		} else if state == .html && line.contains('span.') && line.ends_with('{') {
+		} else if state == .html && line.starts_with('span.') && line.ends_with('{') {
 			// `span.header {` => `<span class='header'>`
 			class := line.find_between('span.', '{').trim_space()
 			source.writeln('<span class="$class">')
 			in_span = true
-		} else if state == .html && line.contains('.') && line.ends_with('{') {
+		} else if state == .html && line.starts_with('.') && line.ends_with('{') {
 			// `.header {` => `<div class='header'>`
 			class := line.find_between('.', '{').trim_space()
 			source.writeln('<div class="$class">')
-		} else if state == .html && line.contains('#') && line.ends_with('{') {
+		} else if state == .html && line.starts_with('#') && line.ends_with('{') {
 			// `#header {` => `<div id='header'>`
 			class := line.find_between('#', '{').trim_space()
 			source.writeln('<div id="$class">')

vlib/v/tests/inout/file.md

@@ -3,6 +3,7 @@
 This is the main content:
 -------------------------
 @content
+Name: @{p1.name}
 -------------------------
 
 @include './footer.md'

vlib/v/tests/inout/tmpl_all_in_one_folder.out

@@ -3,6 +3,7 @@ my header
 This is the main content:
 -------------------------
 some string
+Name: Peter
 -------------------------
 
 my footer

vlib/v/tests/inout/tmpl_all_in_one_folder.vv

@@ -1,4 +1,11 @@
+struct Person {
+mut:
+	name string
+}
+
 fn abc() string {
+	mut p1 := Person{}
+	p1.name = 'Peter'
 	content := 'some string'
 	return $tmpl('file.md')
 }