scanner: fix new string interpolation: print('{n:10}') (fix #16321) (#16325)

examples/vweb/vweb_assets/index.html

@@ -10,4 +10,3 @@
 	<p>@message</p>
 </body>
 </html>
-

vlib/v/scanner/scanner.v

@@ -1185,6 +1185,7 @@ fn (mut s Scanner) ident_string() string {
 		}
 		c := s.text[s.pos]
 		prevc := s.text[s.pos - 1]
+		nextc := s.text[s.pos + 1]
 		if c == scanner.backslash {
 			backslash_count++
 		}
@@ -1206,18 +1207,17 @@ fn (mut s Scanner) ident_string() string {
 		if backslash_count % 2 == 1 && !is_raw && !is_cstr {
 			// Escape `\x`
 			if c == `x` {
-				if s.text[s.pos + 1] == s.quote || !(s.text[s.pos + 1].is_hex_digit()
+				if nextc == s.quote || !(nextc.is_hex_digit() && s.text[s.pos + 2].is_hex_digit()) {
-					&& s.text[s.pos + 2].is_hex_digit()) {
 					s.error(r'`\x` used without two following hex digits')
 				}
 				h_escapes_pos << s.pos - 1
 			}
 			// Escape `\u`
 			if c == `u` {
-				if s.text[s.pos + 1] == s.quote || s.text[s.pos + 2] == s.quote
+				if nextc == s.quote || s.text[s.pos + 2] == s.quote || s.text[s.pos + 3] == s.quote
-					|| s.text[s.pos + 3] == s.quote || s.text[s.pos + 4] == s.quote
+					|| s.text[s.pos + 4] == s.quote || !nextc.is_hex_digit()
-					|| !s.text[s.pos + 1].is_hex_digit() || !s.text[s.pos + 2].is_hex_digit()
+					|| !s.text[s.pos + 2].is_hex_digit() || !s.text[s.pos + 3].is_hex_digit()
-					|| !s.text[s.pos + 3].is_hex_digit() || !s.text[s.pos + 4].is_hex_digit() {
+					|| !s.text[s.pos + 4].is_hex_digit() {
 					s.error(r'`\u` incomplete unicode character value')
 				}
 				u_escapes_pos << s.pos - 1
@@ -1243,27 +1243,11 @@ fn (mut s Scanner) ident_string() string {
 			break
 		}
 		// '{var}' (ignore in vfmt mode) (skip \{)
-		if c == `{` && util.is_name_char(s.text[s.pos + 1]) && prevc != `$` && !is_raw
+		if c == `{` && (util.is_name_char(nextc) || nextc == `@`) && prevc != `$` && !is_raw
 			&& s.count_symbol_before(s.pos - 1, scanner.backslash) % 2 == 0 {
 			// Detect certain strings with "{" that are not interpolation:
 			// e.g. "{init: " (no "}" at the end)
-			mut is_valid_inter := true
+			if s.is_valid_interpolation(s.pos + 1) {
-			for i := s.pos + 1; i < s.text.len; i++ {
-				if s.text[i] == `}` || (s.text[i] == `=` && (s.text[i - 1] in [`!`, `>`, `<`]
-					|| s.text[i + 1] == `=`)) {
-					// No } in this string, so it's not a valid `{x}` interpolation
-					// `!=` `>=` `<=` `==`
-					break
-				}
-				if s.text[i] in [`=`, `:`] {
-					// We reached the end of the line or string without reaching "}".
-					// Also if there's "=", there's no way it's a valid interpolation expression:
-					// e.g. `println("{a.b = 42}")` `println('{foo:bar}')`
-					is_valid_inter = false
-					break
-				}
-			}
-			if is_valid_inter {
 				s.is_inside_string = true
 				s.is_enclosed_inter = true
 				// so that s.pos points to $ at the next step
@@ -1272,27 +1256,11 @@ fn (mut s Scanner) ident_string() string {
 			}
 		}
 		// '{var1}{var2}'
-		if prevc == `{` && util.is_name_char(c) && s.text[s.pos - 2] !in [`$`, `{`] && !is_raw
+		if prevc == `{` && (util.is_name_char(c) || c == `@`) && s.text[s.pos - 2] !in [`$`, `{`]
-			&& s.count_symbol_before(s.pos - 2, scanner.backslash) % 2 == 0 {
+			&& !is_raw && s.count_symbol_before(s.pos - 2, scanner.backslash) % 2 == 0 {
 			// Detect certain strings with "{" that are not interpolation:
 			// e.g. "{init: " (no "}" at the end)
-			mut is_valid_inter := true
+			if s.is_valid_interpolation(s.pos) {
-			for i := s.pos; i < s.text.len; i++ {
-				if s.text[i] == `}` || (s.text[i] == `=` && (s.text[i - 1] in [`!`, `>`, `<`]
-					|| s.text[i + 1] == `=`)) {
-					// No } in this string, so it's not a valid `{x}` interpolation
-					// `!=` `>=` `<=` `==`
-					break
-				}
-				if s.text[i] in [`=`, `:`] {
-					// We reached the end of the line or string without reaching "}".
-					// Also if there's "=", there's no way it's a valid interpolation expression:
-					// e.g. `println("{a.b = 42}")` `println('{foo:bar}')`
-					is_valid_inter = false
-					break
-				}
-			}
-			if is_valid_inter {
 				s.is_inside_string = true
 				s.is_enclosed_inter = true
 				// so that s.pos points to $ at the next step
@@ -1355,6 +1323,33 @@ fn (mut s Scanner) ident_string() string {
 	return lit
 }
 
+fn (s Scanner) is_valid_interpolation(start_pos int) bool {
+	mut is_valid_inter := true
+	mut has_rcbr := false
+	mut is_assign := true
+	for i := start_pos; i < s.text.len - 1; i++ {
+		if s.text[i] == s.quote {
+			break
+		}
+		if s.text[i] == `}` {
+			// No } in this string, so it's not a valid `{x}` interpolation
+			has_rcbr = true
+		}
+		if s.text[i] == `=` && (s.text[i - 1] in [`!`, `>`, `<`] || s.text[i + 1] == `=`) {
+			// `!=` `>=` `<=` `==`
+			is_assign = false
+		}
+		if (s.text[i] == `=` && is_assign) || (s.text[i] == `:` && s.text[i + 1].is_space()) {
+			// We reached the end of the line or string without reaching "}".
+			// Also if there's "=", there's no way it's a valid interpolation expression:
+			// e.g. `println("{a.b = 42}")` `println('{foo:bar}')`
+			is_valid_inter = false
+			break
+		}
+	}
+	return is_valid_inter && has_rcbr
+}
+
 fn decode_h_escape_single(str string, idx int) (int, string) {
 	end_idx := idx + 4 // "\xXX".len == 4
 

vlib/v/tests/string_new_interpolation_test.v

@@ -16,15 +16,27 @@ fn test_string_new_interpolation() {
 	println('{a}{{{{{b}}}}}')
 	assert '{a}{{{{{b}}}}}' == '1{{{{2}}}}'
 
+	// vfmt off
 	s := 'hello'
-	println('{s == 'hello'}')
+	println('{s == "hello"}')
-	assert '{s == 'hello'}' == 'true'
+	assert '{s == "hello"}' == 'true'
-	println('{s != 'hello'}')
+	println('{s != "hello"}')
-	assert '{s != 'hello'}' == 'false'
+	assert '{s != "hello"}' == 'false'
+	// vfmt on
 
 	n := 22
 	println('{n >= 10}')
 	assert '{n >= 10}' == 'true'
 	println('{n <= 10}')
 	assert '{n <= 10}' == 'false'
+
+	println('{n:10}')
+	assert '{n:10}' == '        22'
+
+	f := 2.234
+	println('{f:05.2f}')
+	assert '{f:05.2f}' == '02.23'
+
+	println('{@FILE}')
+	assert '{@FILE}'.contains('string_new_interpolation_test.v')
 }