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End while and if statements with the end token

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This commit is contained in:
Eugen Wissner 2025-01-17 10:11:40 +01:00
parent ef667e3ace
commit e95be9626f
Signed by: belka
GPG Key ID: A27FDC1E8EE902C0
5 changed files with 52 additions and 58 deletions
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18
README.md
View File

@ -34,7 +34,7 @@ program = [ "type" type_definitions ";" ]
[ constant_part ]
{ procedure_definition }
[ variable_part ]
compound_statement ".";
"begin" [ statement_list ] "end" ".";
procedure_definition = "proc" ident formal_parameter_list ";" ( block | "extern" ) ";";
@ -45,14 +45,18 @@ block = [ constant_part ]
constant_part = "const" ident "=" integer { "," ident "=" integer } ";";
variable_part = "var" variable_declarations ";";
statement = compound_statement
| ident ":=" expression
statement = ident ":=" expression
| ident actual_parameter_list
| "while" condition "do" statement
| "if" expression "then" statement [ else statement ];
| while_do
| if_then_else;
while_do = "while" condition "do" [ statement_list ] "end";
if_then_else = "if" expression
"then" [ statement_list ]
[ else statement_list ] "end";
statement_list = statement {";" statement };
compound_statement = "begin" [ statement_list ] "end";
condition = "odd" expression |
expression ("="|"#"|"<"|"<="|">"|">=") expression;
@ -86,7 +90,7 @@ variable_declarations = variable_declaration { ";" variable_declaration };
variable_declaration = ident ":" type_expression;
type_expression = "array" integer "of" type_expression
| "^" type_expression
| "pointer" "to" type_expression
| "record" field_list "end"
| ident;

24
include/elna/source/ast.h
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@ -443,13 +443,11 @@ namespace source
class compound_statement : public statement
{
std::vector<statement *> m_statements;
public:
explicit compound_statement(const struct position position);
virtual void accept(parser_visitor *visitor) override;
std::vector<statement *> statements;
std::vector<statement *>& statements();
compound_statement(const struct position position, std::vector<statement *>&& statements);
virtual void accept(parser_visitor *visitor) override;
virtual ~compound_statement() override;
};
@ -556,8 +554,8 @@ namespace source
class if_statement : public statement
{
expression *m_prerequisite;
statement *m_body;
statement *m_alternative;
compound_statement *m_body;
compound_statement *m_alternative;
public:
/**
@ -567,12 +565,12 @@ namespace source
* \param alternative Statement executed if the condition is not met.
*/
if_statement(const struct position position, expression *prerequisite,
statement *body, statement *alternative = nullptr);
compound_statement *body, compound_statement *alternative = nullptr);
virtual void accept(parser_visitor *visitor) override;
expression& prerequisite();
statement& body();
statement *alternative();
compound_statement& body();
compound_statement *alternative();
virtual ~if_statement() override;
};
@ -583,7 +581,7 @@ namespace source
class while_statement : public statement
{
expression *m_prerequisite;
statement *m_body;
compound_statement *m_body;
public:
/**
@ -592,11 +590,11 @@ namespace source
* \param body Statement executed while the condition is met.
*/
while_statement(const struct position position, expression *prerequisite,
statement *body);
compound_statement *body);
virtual void accept(parser_visitor *visitor) override;
expression& prerequisite();
statement& body();
compound_statement& body();
virtual ~while_statement() override;
};

23
source/ast.cc
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@ -43,7 +43,7 @@ namespace source
void empty_visitor::visit(compound_statement *statement)
{
for (auto& nested_statement : statement->statements())
for (const auto nested_statement : statement->statements)
{
nested_statement->accept(this);
}
@ -766,8 +766,8 @@ namespace source
}
}
compound_statement::compound_statement(const struct position position)
: statement(position)
compound_statement::compound_statement(const struct position position, std::vector<statement *>&& statements)
: statement(position), statements(std::move(statements))
{
}
@ -776,14 +776,9 @@ namespace source
visitor->visit(this);
}
std::vector<statement *>& compound_statement::statements()
{
return m_statements;
}
compound_statement::~compound_statement()
{
for (auto statement : m_statements)
for (auto statement : statements)
{
delete statement;
}
@ -836,7 +831,7 @@ namespace source
}
if_statement::if_statement(const struct position position, expression *prerequisite,
statement *body, statement *alternative)
compound_statement *body, compound_statement *alternative)
: statement(position), m_prerequisite(prerequisite), m_body(body),
m_alternative(alternative)
{
@ -852,12 +847,12 @@ namespace source
return *m_prerequisite;
}
statement& if_statement::body()
compound_statement& if_statement::body()
{
return *m_body;
}
statement *if_statement::alternative()
compound_statement *if_statement::alternative()
{
return m_alternative;
}
@ -874,7 +869,7 @@ namespace source
}
while_statement::while_statement(const struct position position, expression *prerequisite,
statement *body)
compound_statement *body)
: statement(position), m_prerequisite(prerequisite), m_body(body)
{
}
@ -889,7 +884,7 @@ namespace source
return *m_prerequisite;
}
statement& while_statement::body()
compound_statement& while_statement::body()
{
return *m_body;
}

6
source/lexer.ll
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@ -76,6 +76,12 @@ type {
record {
return yy::parser::make_RECORD(this->location);
}
pointer {
return yy::parser::make_POINTER(this->location);
}
to {
return yy::parser::make_TO(this->location);
}
true {
return yy::parser::make_BOOLEAN(true, this->location);
}

39
source/parser.yy
View File

@ -62,8 +62,8 @@
%token <std::string> CHARACTER "character"
%token <std::string> STRING "string"
%token <bool> BOOLEAN
%token IF WHILE DO
%token CONST VAR PROCEDURE ARRAY OF TYPE RECORD
%token IF WHILE DO THEN ELSE
%token CONST VAR PROCEDURE ARRAY OF TYPE RECORD POINTER TO
%token BEGIN_BLOCK END_BLOCK EXTERN
%token LEFT_PAREN RIGHT_PAREN LEFT_SQUARE RIGHT_SQUARE SEMICOLON DOT COMMA
%token AND OR NOT
@ -71,9 +71,6 @@
%token PLUS MINUS MULTIPLICATION DIVISION
%token ASSIGNMENT COLON HAT AT
%precedence THEN
%precedence ELSE
%type <elna::source::literal *> literal;
%type <elna::source::constant_definition *> constant_definition;
%type <std::vector<elna::source::constant_definition *>> constant_part constant_definitions;
@ -84,7 +81,6 @@
%type <elna::source::expression *> expression pointer summand factor comparand logical_operand;
%type <std::vector<elna::source::expression *>> expressions actual_parameter_list;
%type <elna::source::designator_expression *> designator_expression;
%type <elna::source::compound_statement *> compound_statement;
%type <elna::source::assign_statement *> assign_statement;
%type <elna::source::call_statement *> call_statement;
%type <elna::source::while_statement *> while_statement;
@ -167,11 +163,6 @@ procedure_definitions:
procedure_part:
/* no procedure definitions */ {}
| procedure_definitions { std::swap($$, $1); }
compound_statement: BEGIN_BLOCK optional_statements END_BLOCK
{
$$ = new elna::source::compound_statement(elna::source::make_position(@1));
std::swap($$->statements(), $2);
}
assign_statement: designator_expression ASSIGNMENT expression
{
$$ = new elna::source::assign_statement(elna::source::make_position(@1), $1, $3);
@ -181,21 +172,22 @@ call_statement: IDENTIFIER actual_parameter_list
$$ = new elna::source::call_statement(elna::source::make_position(@1), $1);
std::swap($$->arguments(), $2);
}
while_statement: WHILE expression DO statement
while_statement: WHILE expression DO optional_statements END_BLOCK
{
$$ = new elna::source::while_statement(elna::source::make_position(@1),
$2, $4);
auto body = new elna::source::compound_statement(elna::source::make_position(@3), std::move($4));
$$ = new elna::source::while_statement(elna::source::make_position(@1), $2, body);
}
if_statement:
IF expression THEN statement
IF expression THEN optional_statements END_BLOCK
{
$$ = new elna::source::if_statement(elna::source::make_position(@1),
$2, $4);
auto then = new elna::source::compound_statement(elna::source::make_position(@3), std::move($4));
$$ = new elna::source::if_statement(elna::source::make_position(@1), $2, then);
}
| IF expression THEN statement ELSE statement
| IF expression THEN optional_statements ELSE optional_statements END_BLOCK
{
$$ = new elna::source::if_statement(elna::source::make_position(@1),
$2, $4, $6);
auto then = new elna::source::compound_statement(elna::source::make_position(@3), std::move($4));
auto _else = new elna::source::compound_statement(elna::source::make_position(@5), std::move($6));
$$ = new elna::source::if_statement(elna::source::make_position(@1), $2, then, _else);
}
literal:
INTEGER
@ -315,8 +307,7 @@ designator_expression:
$$ = new elna::source::variable_expression(elna::source::make_position(@1), $1);
}
statement:
compound_statement { $$ = $1; }
| assign_statement { $$ = $1; }
assign_statement { $$ = $1; }
| call_statement { $$ = $1; }
| while_statement { $$ = $1; }
| if_statement { $$ = $1; }
@ -344,9 +335,9 @@ type_expression:
{
$$ = new elna::source::array_type_expression(elna::source::make_position(@1), $4, $2);
}
| HAT type_expression
| POINTER TO type_expression
{
$$ = new elna::source::pointer_type_expression(elna::source::make_position(@1), $2);
$$ = new elna::source::pointer_type_expression(elna::source::make_position(@1), $3);
}
| RECORD field_list END_BLOCK
{