342 lines
6.6 KiB
V
342 lines
6.6 KiB
V
// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module compiler
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import (
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strings
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)
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// Returns type if used as expression
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fn (p mut Parser) match_statement(is_expr bool) string {
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p.check(.key_match)
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p.fspace()
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typ, expr := p.tmp_expr()
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if typ.starts_with('array_') {
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p.error('arrays cannot be compared')
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}
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// is it safe to use p.cgen.insert_before ???
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tmp_var := p.get_tmp()
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p.cgen.insert_before('$typ $tmp_var = $expr;')
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p.fspace()
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p.check(.lcbr)
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mut i := 0
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mut all_cases_return := true
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// stores typ of resulting variable
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mut res_typ := ''
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defer {
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p.check(.rcbr)
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}
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for p.tok != .rcbr {
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if p.tok == .key_else {
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p.check(.key_else)
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if p.tok == .arrow {
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p.error(warn_match_arrow)
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}
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// unwrap match if there is only else
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if i == 0 {
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p.fspace()
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if is_expr {
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// statements are dissallowed (if match is expression) so user cant declare variables there and so on
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// allow braces is else
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got_brace := p.tok == .lcbr
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if got_brace {
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p.check(.lcbr)
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}
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p.gen('( ')
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res_typ = p.bool_expression()
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p.gen(' )')
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// allow braces in else
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if got_brace {
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p.check(.rcbr)
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}
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return res_typ
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} else {
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p.returns = false
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p.check(.lcbr)
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p.genln('{ ')
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p.statements()
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p.returns = all_cases_return && p.returns
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return ''
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}
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}
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if is_expr {
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// statements are dissallowed (if match is expression) so user cant declare variables there and so on
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p.gen(':(')
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// allow braces is else
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got_brace := p.tok == .lcbr
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if got_brace {
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p.fspace()
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p.check(.lcbr)
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}
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p.check_types(p.bool_expression(), res_typ)
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// allow braces in else
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if got_brace {
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p.check(.rcbr)
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}
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p.gen(strings.repeat(`)`, i+1))
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return res_typ
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} else {
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p.returns = false
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p.genln('else // default:')
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p.fspace()
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p.check(.lcbr)
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p.genln('{ ')
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p.statements()
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p.returns = all_cases_return && p.returns
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return ''
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}
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}
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if i > 0 {
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if is_expr {
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p.gen(': (')
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} else {
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p.gen('else ')
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}
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} else if is_expr {
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p.gen('(')
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}
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if is_expr {
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p.gen('(')
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} else {
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p.gen('if (')
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}
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ph := p.cgen.add_placeholder()
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// Multiple checks separated by comma
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mut got_comma := false
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for {
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if got_comma {
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p.gen(') || (')
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}
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mut got_string := false
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if typ == 'string' {
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got_string = true
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p.gen('string_eq($tmp_var, ')
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}
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else {
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p.gen('$tmp_var == ')
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}
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p.expected_type = typ
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p.check_types(p.bool_expression(), typ)
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p.expected_type = ''
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if got_string {
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p.gen(')')
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}
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if p.tok != .comma {
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if got_comma {
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p.gen(') ')
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p.cgen.set_placeholder(ph, '(')
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}
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break
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}
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p.check(.comma)
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got_comma = true
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}
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p.gen(')')
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if p.tok == .arrow {
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p.error(warn_match_arrow)
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p.check(.arrow)
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}
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// statements are dissallowed (if match is expression) so user cant declare variables there and so on
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if is_expr {
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p.gen('? (')
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// braces are required for now
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p.check(.lcbr)
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if i == 0 {
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// on the first iteration we set value of res_typ
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res_typ = p.bool_expression()
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} else {
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// later on we check that the value is of res_typ type
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p.check_types(p.bool_expression(), res_typ)
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}
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// braces are required for now
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p.check(.rcbr)
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p.gen(')')
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}
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else {
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p.returns = false
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p.fspace()
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p.check(.lcbr)
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p.genln('{ ')
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p.statements()
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all_cases_return = all_cases_return && p.returns
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// p.gen(')')
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}
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i++
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p.fgen_nl()
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}
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p.error('match must be exhaustive')
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//p.returns = false // only get here when no default, so return is not guaranteed
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return ''
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}
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fn (p mut Parser) switch_statement() {
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p.error('`switch` statement has been removed, use `match` instead:\n' +
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'https://vlang.io/docs#match')
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}
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fn (p mut Parser) if_statement(is_expr bool, elif_depth int) string {
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if is_expr {
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//if p.fileis('if_expr') {
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//println('IF EXPR')
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//}
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p.inside_if_expr = true
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p.gen('((')
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}
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else {
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p.gen('if (')
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}
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p.next()
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p.fspace()
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// `if a := opt() { }` syntax
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if p.tok == .name && p.peek() == .decl_assign {
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p.check_not_reserved()
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option_tmp := p.get_tmp()
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var_name := p.lit
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if p.known_var(var_name) {
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p.error('redefinition of `$var_name`')
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}
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p.open_scope()
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p.next()
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p.check(.decl_assign)
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p.is_var_decl = true
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option_type, expr := p.tmp_expr()// := p.bool_expression()
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if !option_type.starts_with('Option_') {
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p.error('`if x := opt() {` syntax requires a function that returns an optional value')
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}
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p.is_var_decl = false
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typ := option_type[7..]
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// Option_User tmp = get_user(1);
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// if (tmp.ok) {
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// User user = *(User*)tmp.data;
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// [statements]
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// }
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p.cgen.insert_before('$option_type $option_tmp = $expr; ')
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p.check(.lcbr)
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p.genln(option_tmp + '.ok) {')
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p.genln('$typ $var_name = *($typ*) $option_tmp . data;')
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p.register_var(Var {
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name: var_name
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typ: typ
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is_mut: false // TODO
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is_used: true // TODO
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//is_alloc: p.is_alloc || typ.starts_with('array_')
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//line_nr: p.tokens[ var_token_idx ].line_nr
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//token_idx: var_token_idx
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})
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p.statements()
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p.close_scope()
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p.returns = false
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return 'void'
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} else {
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p.check_types(p.bool_expression(), 'bool')
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}
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if is_expr {
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p.gen(') ? (')
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}
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else {
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p.genln(') {')
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}
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p.fspace()
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p.check(.lcbr)
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mut typ := ''
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// if { if hack
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if p.tok == .key_if && p.inside_if_expr {
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typ = p.factor()
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p.next()
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}
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else {
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typ = p.statements()
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}
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if_returns := p.returns
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p.returns = false
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if p.tok == .key_else {
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if !p.inside_if_expr {
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p.fgen_nl()
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}
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p.check(.key_else)
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p.fspace()
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if p.tok == .key_if {
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if is_expr {
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p.gen(') : (')
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nested := p.if_statement(is_expr, elif_depth + 1)
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nested_returns := p.returns
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p.returns = if_returns && nested_returns
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return nested
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}
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else {
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p.gen(' else ')
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nested := p.if_statement(is_expr, 0)
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nested_returns := p.returns
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p.returns = if_returns && nested_returns
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return nested
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}
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// return ''
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}
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if is_expr {
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p.gen(') : (')
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}
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else {
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p.genln(' else { ')
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}
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p.check(.lcbr)
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// statements() returns the type of the last statement
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first_typ := typ
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typ = p.statements()
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p.inside_if_expr = false
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if is_expr {
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p.check_types(first_typ, typ)
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p.gen(strings.repeat(`)`, 2 * (elif_depth + 1)))
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}
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else_returns := p.returns
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p.returns = if_returns && else_returns
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return typ
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}
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p.inside_if_expr = false
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if p.fileis('test_test') {
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println('if ret typ="$typ" line=$p.scanner.line_nr')
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}
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return typ
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}
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