From 4d1f721558ef935a02274f04b90501e1b0837c79 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Sun, 8 Dec 2019 20:06:00 +0300
Subject: [PATCH] fix "" string interpolation bug

---
 vlib/builtin/string_test.v        |   8 ++
 vlib/compiler/parser.v            | 148 ----------------------------
 vlib/compiler/scanner.v           |  19 ++--
 vlib/compiler/string_expression.v | 154 ++++++++++++++++++++++++++++++
 4 files changed, 173 insertions(+), 156 deletions(-)
 create mode 100644 vlib/compiler/string_expression.v

diff --git a/vlib/builtin/string_test.v b/vlib/builtin/string_test.v
index a42aad0d81..ecc1dd72f7 100644
--- a/vlib/builtin/string_test.v
+++ b/vlib/builtin/string_test.v
@@ -565,3 +565,11 @@ fn test_inter_before_comp_if() {
 	}
 }
 
+fn test_double_quote_inter() {
+	a := 1
+	b := 2
+	println("${a} ${b}")
+	assert "${a} ${b}" == "1 2"
+	assert '${a} ${b}' == "1 2"
+}
+
diff --git a/vlib/compiler/parser.v b/vlib/compiler/parser.v
index f102fb85b8..1c5c74e866 100644
--- a/vlib/compiler/parser.v
+++ b/vlib/compiler/parser.v
@@ -2280,154 +2280,6 @@ fn format_str(_str string) string {
 	return str
 }
 
-fn (p mut Parser) string_expr() {
-	is_raw := p.tok == .name && p.lit == 'r'
-	is_cstr := p.tok == .name && p.lit == 'c'
-	if is_raw || is_cstr {
-		p.next()
-	}
-	str := p.lit
-	// No ${}, just return a simple string
-	if p.peek() != .str_dollar || is_raw {
-		f := if is_raw { cescaped_path(str) } else { format_str(str) }
-		// `C.puts('hi')` => `puts("hi");`
-		/*
-		Calling a C function sometimes requires a call to a string method
-		C.fun('ssss'.to_wide()) =>  fun(string_to_wide(tos3("ssss")))
-		*/
-		if (p.calling_c && p.peek() != .dot) || is_cstr || (p.pref.translated && p.mod == 'main') {
-			p.gen('"$f"')
-		}
-		else if p.is_sql {
-			p.gen("'$str'")
-		}
-		else if p.is_js {
-			p.gen('tos("$f")')
-		}
-		else {
-			p.gen('tos3("$f")')
-		}
-		p.next()
-		return
-	}
-	$if js {
-		p.error('js backend does not support string formatting yet')
-	}
-	p.is_alloc = true // $ interpolation means there's allocation
-	mut args := '"'
-	mut format := '"'
-	mut complex_inter := false  // for vfmt
-	for p.tok == .str {
-		// Add the string between %d's
-		p.lit = p.lit.replace('%', '%%')
-		format += format_str(p.lit)
-		p.next()// skip $
-		if p.tok != .str_dollar {
-			continue
-		}
-		// Handle .dollar
-		p.check(.str_dollar)
-		// If there's no string after current token, it means we are in
-		// a complex expression (`${...}`)
-		if p.peek() != .str {
-			p.fgen('{')
-			complex_inter = true
-		}
-		// Get bool expr inside a temp var
-		typ, val_ := p.tmp_expr()
-		val := val_.trim_space()
-		args += ', $val'
-		if typ == 'string' {
-			// args += '.str'
-			// printf("%.*s", a.len, a.str) syntax
-			args += '.len, ${val}.str'
-		}
-		if typ == 'ustring' {
-			args += '.len, ${val}.s.str'
-		}
-		if typ == 'bool' {
-			//args += '.len, ${val}.str'
-		}
-		// Custom format? ${t.hour:02d}
-		custom := p.tok == .colon
-		if custom {
-			mut cformat := ''
-			p.next()
-			if p.tok == .dot {
-				cformat += '.'
-				p.next()
-			}
-			if p.tok == .minus { // support for left aligned formatting
-				cformat += '-'
-				p.next()
-			}
-			cformat += p.lit// 02
-			p.next()
-			fspec := p.lit // f
-			cformat += fspec
-			if fspec == 's' {
-				//println('custom str F=$cformat | format_specifier: "$fspec" | typ: $typ ')
-				if typ != 'string' {
-					p.error('only V strings can be formatted with a :${cformat} format, but you have given "${val}", which has type ${typ}')
-				}
-				args = args.all_before_last('${val}.len, ${val}.str') + '${val}.str'
-			}
-			format += '%$cformat'
-			p.next()
-		}
-		else {
-			f := p.typ_to_fmt(typ, 0)
-			if f == '' {
-				is_array := typ.starts_with('array_')
-				typ2 := p.table.find_type(typ)
-				has_str_method := p.table.type_has_method(typ2, 'str')
-				if is_array || has_str_method {
-					if is_array && !has_str_method {
-						p.gen_array_str(typ2)
-					}
-					tmp_var := p.get_tmp()
-					p.cgen.insert_before('string $tmp_var = ${typ}_str(${val});')
-					args = args.all_before_last(val) + '${tmp_var}.len, ${tmp_var}.str'
-					format += '%.*s '
-				}
-				else {
-					p.error('unhandled sprintf format "$typ" ')
-				}
-			}
-			format += f
-		}
-		//println('interpolation format is: |${format}| args are: |${args}| ')
-	}
-	if complex_inter {
-		p.fgen('}')
-	}
-	//p.fgen('\'')
-	// println("hello %d", num) optimization.
-	if p.cgen.nogen {
-		return
-	}
-	// println: don't allocate a new string, just print	it.
-	$if !windows {
-		cur_line := p.cgen.cur_line.trim_space()
-		if cur_line == 'println (' && p.tok != .plus {
-			p.cgen.resetln(cur_line.replace('println (', 'printf('))
-			p.gen('$format\\n$args')
-			return
-		}
-	}
-	// '$age'! means the user wants this to be a tmp string (uses global buffer, no allocation,
-	// won't be used	again)
-	// TODO remove this hack, do this automatically
-	if p.tok == .not {
-		p.check(.not)
-		p.gen('_STR_TMP($format$args)')
-	}
-	else {
-		// Otherwise do len counting + allocation + sprintf
-		p.gen('_STR($format$args)')
-	}
-}
-
 // m := map[string]int{}
 // m := { 'one': 1 }
 fn (p mut Parser) map_init() string {
diff --git a/vlib/compiler/scanner.v b/vlib/compiler/scanner.v
index a28e27fc58..c1cf0fc74d 100644
--- a/vlib/compiler/scanner.v
+++ b/vlib/compiler/scanner.v
@@ -298,14 +298,15 @@ fn (s mut Scanner) scan() ScanRes {
 				s.inside_string = false
 			}
 		}
+		// end of `$expr`
 		if s.inter_start && next_char != `.` {
 			s.inter_end = true
 			s.inter_start = false
 		}
 		if s.pos == 0 && next_char == ` ` {
-			s.pos++
 			//If a single letter name at the start of the file, increment
 			//Otherwise the scanner would be stuck at s.pos = 0
+			s.pos++
 		}
 		return scan_res(.name, name)
 	}
@@ -390,8 +391,7 @@ fn (s mut Scanner) scan() ScanRes {
 		return scan_res(.lcbr, '')
 	}
 	 `$` {
-	// 	if s.inter_start {
-		if s.inside_string {// || s.inter_start {
+		if s.inside_string {
 			return scan_res(.str_dollar, '')
 		}  else {
 			return scan_res(.dollar, '')
@@ -402,8 +402,7 @@ fn (s mut Scanner) scan() ScanRes {
 		// s = `hello ${name} !`
 		if s.inside_string {
 			s.pos++
-			// TODO UNNEEDED?
-			if s.text[s.pos] == single_quote {
+			if s.text[s.pos] == s.quote {
 				s.inside_string = false
 				return scan_res(.str, '')
 			}
@@ -704,15 +703,19 @@ fn (s mut Scanner) ident_string() string {
 		if c == `0` && s.pos > 5 && s.expect('\\x0', s.pos - 3) {
 			s.error('0 character in a string literal')
 		}
-		// ${var}
-		if c == `{` && prevc == `$` && !is_raw && !s.is_fmt && s.count_symbol_before(s.pos-2, slash) % 2 == 0 {
+		// ${var} (ignore in vfmt mode)
+		if c == `{` && prevc == `$` && !is_raw && !s.is_fmt &&
+			s.count_symbol_before(s.pos-2, slash) % 2 == 0
+		{
 			s.inside_string = true
 			// so that s.pos points to $ at the next step
 			s.pos -= 2
 			break
 		}
 		// $var
-		if (c.is_letter() || c == `_`) && prevc == `$` && !s.is_fmt && !is_raw && s.count_symbol_before(s.pos-2, slash) % 2 == 0 {
+		if (c.is_letter() || c == `_`) && prevc == `$` && !s.is_fmt &&
+			!is_raw && s.count_symbol_before(s.pos-2, slash) % 2 == 0
+		{
 			s.inside_string = true
 			s.inter_start = true
 			s.pos -= 2
diff --git a/vlib/compiler/string_expression.v b/vlib/compiler/string_expression.v
new file mode 100644
index 0000000000..26bf1141bb
--- /dev/null
+++ b/vlib/compiler/string_expression.v
@@ -0,0 +1,154 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+module compiler
+
+fn (p mut Parser) string_expr() {
+	is_raw := p.tok == .name && p.lit == 'r'
+	is_cstr := p.tok == .name && p.lit == 'c'
+	if is_raw || is_cstr {
+		p.next()
+	}
+	str := p.lit
+	// No ${}, just return a simple string
+	if p.peek() != .str_dollar || is_raw {
+		f := if is_raw { cescaped_path(str) } else { format_str(str) }
+		// `C.puts('hi')` => `puts("hi");`
+		/*
+		Calling a C function sometimes requires a call to a string method
+		C.fun('ssss'.to_wide()) =>  fun(string_to_wide(tos3("ssss")))
+		*/
+		if (p.calling_c && p.peek() != .dot) || is_cstr || (p.pref.translated && p.mod == 'main') {
+			p.gen('"$f"')
+		}
+		else if p.is_sql {
+			p.gen("'$str'")
+		}
+		else if p.is_js {
+			p.gen('tos("$f")')
+		}
+		else {
+			p.gen('tos3("$f")')
+		}
+		p.next()
+		return
+	}
+	$if js {
+		p.error('js backend does not support string formatting yet')
+	}
+	p.is_alloc = true // $ interpolation means there's allocation
+	mut args := '"'
+	mut format := '"'
+	mut complex_inter := false  // for vfmt
+	for p.tok == .str {
+		// Add the string between %d's
+		p.lit = p.lit.replace('%', '%%')
+		format += format_str(p.lit)
+		p.next()// skip $
+		if p.tok != .str_dollar {
+			continue
+		}
+		// Handle .dollar
+		p.check(.str_dollar)
+		// If there's no string after current token, it means we are in
+		// a complex expression (`${...}`)
+		if p.peek() != .str {
+			p.fgen('{')
+			complex_inter = true
+		}
+		// Get bool expr inside a temp var
+		typ, val_ := p.tmp_expr()
+		val := val_.trim_space()
+		args += ', $val'
+		if typ == 'string' {
+			// args += '.str'
+			// printf("%.*s", a.len, a.str) syntax
+			args += '.len, ${val}.str'
+		}
+		if typ == 'ustring' {
+			args += '.len, ${val}.s.str'
+		}
+		if typ == 'bool' {
+			//args += '.len, ${val}.str'
+		}
+		// Custom format? ${t.hour:02d}
+		custom := p.tok == .colon
+		if custom {
+			mut cformat := ''
+			p.next()
+			if p.tok == .dot {
+				cformat += '.'
+				p.next()
+			}
+			if p.tok == .minus { // support for left aligned formatting
+				cformat += '-'
+				p.next()
+			}
+			cformat += p.lit// 02
+			p.next()
+			fspec := p.lit // f
+			cformat += fspec
+			if fspec == 's' {
+				//println('custom str F=$cformat | format_specifier: "$fspec" | typ: $typ ')
+				if typ != 'string' {
+					p.error('only V strings can be formatted with a :${cformat} format, but you have given "${val}", which has type ${typ}')
+				}
+				args = args.all_before_last('${val}.len, ${val}.str') + '${val}.str'
+			}
+			format += '%$cformat'
+			p.next()
+		}
+		else {
+			f := p.typ_to_fmt(typ, 0)
+			if f == '' {
+				is_array := typ.starts_with('array_')
+				typ2 := p.table.find_type(typ)
+				has_str_method := p.table.type_has_method(typ2, 'str')
+				if is_array || has_str_method {
+					if is_array && !has_str_method {
+						p.gen_array_str(typ2)
+					}
+					tmp_var := p.get_tmp()
+					p.cgen.insert_before('string $tmp_var = ${typ}_str(${val});')
+					args = args.all_before_last(val) + '${tmp_var}.len, ${tmp_var}.str'
+					format += '%.*s '
+				}
+				else {
+					p.error('unhandled sprintf format "$typ" ')
+				}
+			}
+			format += f
+		}
+		//println('interpolation format is: |${format}| args are: |${args}| ')
+	}
+	if complex_inter {
+		p.fgen('}')
+	}
+	//p.fgen('\'')
+	// println("hello %d", num) optimization.
+	if p.cgen.nogen {
+		return
+	}
+	// println: don't allocate a new string, just print	it.
+	$if !windows {
+		cur_line := p.cgen.cur_line.trim_space()
+		if cur_line == 'println (' && p.tok != .plus {
+			p.cgen.resetln(cur_line.replace('println (', 'printf('))
+			p.gen('$format\\n$args')
+			return
+		}
+	}
+	// '$age'! means the user wants this to be a tmp string (uses global buffer, no allocation,
+	// won't be used	again)
+	// TODO remove this hack, do this automatically
+	if p.tok == .not {
+		p.check(.not)
+		p.gen('_STR_TMP($format$args)')
+	}
+	else {
+		// Otherwise do len counting + allocation + sprintf
+		p.gen('_STR($format$args)')
+	}
+}
+