Implement switch expression

Author: iluuu1994

Zend/tests/switch/001.phpt

@@ -0,0 +1,36 @@
+--TEST--
+Basic switch expression functionality test
+--FILE--
+<?php
+
+function wordify($x) {
+    return $x switch {
+        0 => 'Zero',
+        1 => 'One',
+        2 => 'Two',
+        3 => 'Three',
+        4 => 'Four',
+        5 => 'Five',
+        6 => 'Six',
+        7 => 'Seven',
+        8 => 'Eight',
+        9 => 'Nine',
+    };
+}
+
+for ($i = 0; $i <= 9; $i++) {
+    print wordify($i) . "\n";
+}
+
+?>
+--EXPECT--
+Zero
+One
+Two
+Three
+Four
+Five
+Six
+Seven
+Eight
+Nine

Zend/tests/switch/002.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Switch expression omit trailing comma
+--FILE--
+<?php
+
+function print_bool($bool) {
+    echo $bool switch {
+        true => "true\n",
+        false => "false\n"
+    };
+}
+
+print_bool(true);
+print_bool(false);
+
+?>
+--EXPECT--
+true
+false

Zend/tests/switch/003.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Switch expression default case
+--FILE--
+<?php
+
+function get_value($i) {
+    return $i switch {
+        1 => 1,
+        2 => 2,
+        default => 'default',
+    };
+}
+
+echo get_value(0) . "\n";
+echo get_value(1) . "\n";
+echo get_value(2) . "\n";
+echo get_value(3) . "\n";
+
+?>
+--EXPECT--
+default
+1
+2
+default

Zend/tests/switch/004.phpt

@@ -0,0 +1,31 @@
+--TEST--
+Switch expression with true as expression
+--FILE--
+<?php
+
+function get_range($i) {
+    return true switch {
+        $i >= 50 => '50+',
+        $i >= 40 => '40-50',
+        $i >= 30 => '30-40',
+        $i >= 20 => '20-30',
+        $i >= 10 => '10-20',
+        default => '0-10',
+    };
+}
+
+echo get_range(22) . "\n";
+echo get_range(0) . "\n";
+echo get_range(59) . "\n";
+echo get_range(13) . "\n";
+echo get_range(39) . "\n";
+echo get_range(40) . "\n";
+
+?>
+--EXPECT--
+20-30
+0-10
+50+
+10-20
+30-40
+40-50

Zend/tests/switch/005.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Switch expression discarding result
+--FILE--
+<?php
+
+1 switch {
+    1 => print "Executed\n",
+};
+
+?>
+--EXPECT--
+Executed

Zend/tests/switch/006.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Switch expression with no cases
+--FILE--
+<?php
+
+$x = true switch {};
+
+?>
+--EXPECTF--
+Fatal error: Uncaught InvalidArgumentException in %s:%d
+Stack trace:
+#0 {main}
+  thrown in %s on line %d

Zend/tests/switch/007.phpt

@@ -0,0 +1,26 @@
+--TEST--
+Switch expression exception on unhandled case
+--FILE--
+<?php
+
+function get_value($i) {
+    return $i switch {
+        1 => 1,
+        2 => 2,
+    };
+}
+
+echo get_value(1) . "\n";
+echo get_value(2) . "\n";
+echo get_value(3) . "\n";
+
+?>
+--EXPECTF--
+1
+2
+
+Fatal error: Uncaught InvalidArgumentException in %s
+Stack trace:
+#0 %s: get_value(3)
+#1 {main}
+  thrown in %s on line %d

Zend/tests/switch/008.phpt

@@ -0,0 +1,23 @@
+--TEST--
+Switch expression precedence
+--FILE--
+<?php
+
+print !true switch {
+    false => "! has higher precedence\n"
+};
+
+$throwableInterface = Throwable::class;
+print new RuntimeException() instanceof $throwableInterface switch {
+    true => "instanceof has higher precedence\n"
+};
+
+print 10 ** 2 switch {
+    100 => "** has higher precedence\n"
+};
+
+?>
+--EXPECT--
+! has higher precedence
+instanceof has higher precedence
+** has higher precedence

Zend/zend_compile.c

@@ -5037,20 +5037,27 @@ static zend_bool should_use_jumptable(zend_ast_list *cases, zend_uchar jumptable
 	}
 }
 
-void zend_compile_switch(zend_ast *ast) /* {{{ */
+void zend_compile_switch(znode *result, zend_ast *ast) /* {{{ */
 {
 	zend_ast *expr_ast = ast->child[0];
 	zend_ast_list *cases = zend_ast_get_list(ast->child[1]);
 
 	uint32_t i;
 	zend_bool has_default_case = 0;
+	zend_bool is_switch_expr = (ast->attr & ZEND_SWITCH_EXPRESSION) != 0;
 
 	znode expr_node, case_node;
 	zend_op *opline;
 	uint32_t *jmpnz_opnums, opnum_default_jmp, opnum_switch = (uint32_t)-1;
 	zend_uchar jumptable_type;
 	HashTable *jumptable = NULL;
 
+	// If the switch expression has no cases the result is never set
+	if (result != NULL) {
+		result->op_type = IS_CONST;
+		ZVAL_NULL(&result->u.constant);
+	}
+
 	zend_compile_expr(&expr_node, expr_ast);
 
 	zend_begin_loop(ZEND_FREE, &expr_node, 1);
@@ -5114,6 +5121,7 @@ void zend_compile_switch(zend_ast *ast) /* {{{ */
 	}
 
 	opnum_default_jmp = zend_emit_jump(0);
+	zend_bool is_first_case = 1;
 
 	for (i = 0; i < cases->children; ++i) {
 		zend_ast *case_ast = cases->child[i];
@@ -5146,7 +5154,23 @@ void zend_compile_switch(zend_ast *ast) /* {{{ */
 			}
 		}
 
-		zend_compile_stmt(stmt_ast);
+		if (is_switch_expr) {
+			znode cond_stmt_node;
+			zend_compile_expr(&cond_stmt_node, stmt_ast);
+
+			if (is_first_case) {
+				zend_emit_op_tmp(result, ZEND_QM_ASSIGN, &cond_stmt_node, NULL);
+				is_first_case = 0;
+			} else {
+				zend_op *opline_qm_assign = zend_emit_op(NULL, ZEND_QM_ASSIGN, &cond_stmt_node, NULL);
+				SET_NODE(opline_qm_assign->result, result);
+			}
+
+			zend_ast *break_ast = zend_ast_create(ZEND_AST_BREAK, NULL);
+			zend_compile_break_continue(break_ast);
+		} else {
+			zend_compile_stmt(stmt_ast);
+		}
 	}
 
 	if (!has_default_case) {
@@ -5156,6 +5180,20 @@ void zend_compile_switch(zend_ast *ast) /* {{{ */
 			opline = &CG(active_op_array)->opcodes[opnum_switch];
 			opline->extended_value = get_next_op_number();
 		}
+
+		// Generate default case for switch expression
+		if (is_switch_expr) {
+			zval exception_name;
+			ZVAL_STRING(&exception_name, "InvalidArgumentException");
+			zend_ast *exception_name_ast = zend_ast_create_zval(&exception_name);
+
+			zend_ast *exception_args_ast = zend_ast_create_list(0, ZEND_AST_ARG_LIST);
+			zend_ast *new_exception_ast = zend_ast_create(ZEND_AST_NEW, exception_name_ast, exception_args_ast);
+			zend_ast *throw_ast = zend_ast_create(ZEND_AST_THROW, new_exception_ast);
+			zend_compile_throw(throw_ast);
+
+			zval_ptr_dtor(&exception_name);
+		}
 	}
 
 	zend_end_loop(get_next_op_number(), &expr_node);
@@ -8782,7 +8820,7 @@ void zend_compile_stmt(zend_ast *ast) /* {{{ */
 			zend_compile_if(ast);
 			break;
 		case ZEND_AST_SWITCH:
-			zend_compile_switch(ast);
+			zend_compile_switch(NULL, ast);
 			break;
 		case ZEND_AST_TRY:
 			zend_compile_try(ast);
@@ -8965,6 +9003,9 @@ void zend_compile_expr(znode *result, zend_ast *ast) /* {{{ */
 		case ZEND_AST_ARROW_FUNC:
 			zend_compile_func_decl(result, ast, 0);
 			return;
+		case ZEND_AST_SWITCH:
+			zend_compile_switch(result, ast);
+			break;
 		default:
 			ZEND_ASSERT(0 /* not supported */);
 	}

Zend/zend_compile.h

@@ -1001,6 +1001,9 @@ static zend_always_inline int zend_check_arg_send_type(const zend_function *zf,
 /* Attribute for ternary inside parentheses */
 #define ZEND_PARENTHESIZED_CONDITIONAL 1
 
+/* Attribute for switch expression */
+#define ZEND_SWITCH_EXPRESSION 1
+
 /* For "use" AST nodes and the seen symbol table */
 #define ZEND_SYMBOL_CLASS    (1<<0)
 #define ZEND_SYMBOL_FUNCTION (1<<1)

Zend/zend_language_parser.y

@@ -74,6 +74,7 @@ static YYSIZE_T zend_yytnamerr(char*, const char*);
 %left T_SL T_SR
 %left '+' '-'
 %left '*' '/' '%'
+%precedence T_SWITCH
 %precedence '!'
 %precedence T_INSTANCEOF
 %precedence '~' T_INT_CAST T_DOUBLE_CAST T_STRING_CAST T_ARRAY_CAST T_OBJECT_CAST T_BOOL_CAST T_UNSET_CAST '@'
@@ -257,6 +258,7 @@ static YYSIZE_T zend_yytnamerr(char*, const char*);
 %type <ast> isset_variable type return_type type_expr type_without_static
 %type <ast> identifier type_expr_without_static union_type_without_static
 %type <ast> inline_function union_type
+%type <ast> switch_expr_case_list non_empty_switch_expr_case_list switch_expr_case
 
 %type <num> returns_ref function fn is_reference is_variadic variable_modifiers
 %type <num> method_modifiers non_empty_member_modifiers member_modifier
@@ -594,6 +596,24 @@ case_separator:
 	|	';'
 ;
 
+switch_expr_case_list:
+		%empty { $$ = zend_ast_create_list(0, ZEND_AST_SWITCH_LIST); }
+	|	non_empty_switch_expr_case_list possible_comma { $$ = $1; }
+;
+
+non_empty_switch_expr_case_list:
+		switch_expr_case
+			{ $$ = zend_ast_create_list(1, ZEND_AST_SWITCH_LIST, $1); }
+	|	non_empty_switch_expr_case_list ',' switch_expr_case
+			{ $$ = zend_ast_list_add($1, $3); }
+;
+
+switch_expr_case:
+		expr T_DOUBLE_ARROW expr
+			{ $$ = zend_ast_create(ZEND_AST_SWITCH_CASE, $1, $3); }
+	|	T_DEFAULT T_DOUBLE_ARROW expr
+			{ $$ = zend_ast_create(ZEND_AST_SWITCH_CASE, NULL, $3); }
+;
 
 while_statement:
 		statement { $$ = $1; }
@@ -1021,6 +1041,10 @@ expr:
 	|	T_YIELD_FROM expr { $$ = zend_ast_create(ZEND_AST_YIELD_FROM, $2); CG(extra_fn_flags) |= ZEND_ACC_GENERATOR; }
 	|	inline_function { $$ = $1; }
 	|	T_STATIC inline_function { $$ = $2; ((zend_ast_decl *) $$)->flags |= ZEND_ACC_STATIC; }
+	|	expr T_SWITCH '{' switch_expr_case_list '}' {
+			$$ = zend_ast_create(ZEND_AST_SWITCH, $1, $4);
+			$$->attr = ZEND_SWITCH_EXPRESSION;
+		}
 ;