all: add r and R switches for repeating in string interpolation, '${"abc":3r}' == 'abcabcabc' (#20197)

vlib/builtin/string_int_test.v

@@ -350,3 +350,17 @@ fn test_interpolate_literal_limits() {
 	assert '10 ${u32(0o377777_77777)}' == '10 4294967295'
 	assert '11 ${i64(-2147483647)}' == '11 -2147483647'
 }
+
+fn test_string_repetition() {
+	a := 'pippo'
+	assert '${'pera':r}' == ''
+	assert '${'pera':R}' == ''
+	assert '${'pera':0r}' == ''
+	assert '${'pera':0R}' == ''
+	assert '${'pera':1r}' == 'pera'
+	assert '${'pera':1R}' == 'PERA'
+	assert '${'pera':2r}' == 'perapera'
+	assert '${'pera':2R}' == 'PERAPERA'
+	assert '${a:2r}' == 'pippopippo'
+	assert '${a:2R}' == 'PIPPOPIPPO'
+}

vlib/builtin/string_interpolation.v

@@ -33,6 +33,7 @@ pub enum StrIntpType {
 	si_g64
 	si_s
 	si_p
+	si_r
 	si_vp
 }
 
@@ -56,6 +57,7 @@ pub fn (x StrIntpType) str() string {
 		.si_e64 { 'f64' } // e64 format use f64 data
 		.si_s { 's' }
 		.si_p { 'p' }
+		.si_r { 'r' } // repeat string
 		.si_vp { 'vp' }
 	}
 }
@@ -75,6 +77,7 @@ pub mut:
 	d_f32 f32
 	d_f64 f64
 	d_s   string
+	d_r   string
 	d_p   voidptr
 	d_vp  voidptr
 }
@@ -224,6 +227,27 @@ fn (data &StrIntpData) process_str_intp_data(mut sb strings.Builder) {
 			return
 		}
 
+		if typ == .si_r {
+			if width > 0 {
+				mut s := ''
+				if upper_case {
+					s = data.d.d_s.to_upper()
+				} else {
+					s = data.d.d_s.clone()
+				}
+
+				for _ in 1 .. (1 + (if width > 0 {
+					width
+				} else {
+					0
+				})) {
+					sb.write_string(s)
+				}
+				s.free()
+			}
+			return
+		}
+
 		// signed int
 		if typ in [.si_i8, .si_i16, .si_i32, .si_i64] {
 			mut d := data.d.d_i64

vlib/v/checker/str.v

@@ -68,7 +68,7 @@ fn (mut c Checker) string_inter_lit(mut node ast.StringInterLiteral) ast.Type {
 		mut fmt := node.fmts[i]
 		// analyze and validate format specifier
 		if fmt !in [`E`, `F`, `G`, `e`, `f`, `g`, `d`, `u`, `x`, `X`, `o`, `c`, `s`, `S`, `p`,
-			`b`, `_`] {
+			`b`, `_`, `r`, `R`] {
 			c.error('unknown format specifier `${fmt:c}`', node.fmt_poss[i])
 		}
 		if fmt == `_` { // set default representation for type if none has been given
@@ -99,14 +99,14 @@ fn (mut c Checker) string_inter_lit(mut node ast.StringInterLiteral) ast.Type {
 				&& fmt !in [`d`, `c`, `x`, `X`, `o`, `u`, `x`, `X`, `o`, `b`])
 				|| (typ.is_float() && fmt !in [`E`, `F`, `G`, `e`, `f`, `g`])
 				|| (typ.is_pointer() && fmt !in [`p`, `x`, `X`])
-				|| (typ.is_string() && fmt !in [`s`, `S`])
+				|| (typ.is_string() && fmt !in [`s`, `S`, `r`, `R`])
 				|| (typ.idx() in [ast.i64_type_idx, ast.f64_type_idx] && fmt == `c`))
 				&& !(typ.is_ptr() && fmt in [`p`, `x`, `X`]) {
 				c.error('illegal format specifier `${fmt:c}` for type `${c.table.get_type_name(ftyp)}`',
 					node.fmt_poss[i])
 			}
 			if c.table.final_sym(typ).kind in [.array, .array_fixed, .struct_, .interface_, .none_, .map, .sum_type]
-				&& fmt in [`E`, `F`, `G`, `e`, `f`, `g`, `d`, `u`, `x`, `X`, `o`, `c`, `p`, `b`]
+				&& fmt in [`E`, `F`, `G`, `e`, `f`, `g`, `d`, `u`, `x`, `X`, `o`, `c`, `p`, `b`, `r`, `R`]
 				&& !(typ.is_ptr() && fmt in [`p`, `x`, `X`]) {
 				c.error('illegal format specifier `${fmt:c}` for type `${c.table.get_type_name(ftyp)}`',
 					node.fmt_poss[i])

vlib/v/gen/c/auto_str_methods.v

@@ -1139,6 +1139,7 @@ fn data_str(x StrIntpType) string {
 		.si_e32 { 'd_f32' } // e32 format use f32 data
 		.si_e64 { 'd_f64' } // e64 format use f64 data
 		.si_s { 'd_s' }
+		.si_r { 'd_r' } // repeat string
 		.si_p { 'd_p' }
 		.si_vp { 'd_vp' }
 	}

vlib/v/gen/c/str_intp.v

@@ -76,6 +76,8 @@ fn (mut g Gen) str_format(node ast.StringInterLiteral, i int, fmts []u8) (u64, s
 		}
 		*/
 		fmt_type = .si_s
+	} else if fspec in [`r`, `R`] {
+		fmt_type = .si_r
 	} else if typ.is_float() {
 		if fspec in [`g`, `G`] {
 			match typ {

vlib/v/gen/js/auto_str_methods.v

@@ -125,6 +125,7 @@ pub enum StrIntpType {
 	si_g64
 	si_s
 	si_p
+	si_r
 	si_vp
 }
 
@@ -148,6 +149,7 @@ pub fn type_to_str(x StrIntpType) string {
 		.si_e64 { return 'f64' } // e64 format use f64 data
 		.si_s { return 's' }
 		.si_p { return 'p' }
+		.si_r { return 'r' } // repeat string
 		.si_vp { return 'vp' }
 	}
 }
@@ -172,6 +174,7 @@ pub fn data_str(x StrIntpType) string {
 		.si_e64 { return 'd_f64' } // e64 format use f64 data
 		.si_s { return 'd_s' }
 		.si_p { return 'd_p' }
+		.si_r { return 'd_r' } // repeat string
 		.si_vp { return 'd_vp' }
 	}
 }