/*
 * This Source Code Form is subject to the terms of the Mozilla Public License
 * v. 2.0. If a copy of the MPL was not distributed with this file, You can
 * obtain one at http://mozilla.org/MPL/2.0/.
 */
%require "3.2"
%language "c++"

%code requires {
    #include <cstdint>
    #include <iostream>
    #include "elna/source/driver.h"

    #if !defined(yyFlexLexerOnce)
        #include <FlexLexer.h>
    #endif

    namespace elna::source
    {
    class lexer;
    }
}

%code provides {
    namespace elna::source
    {

    class lexer: public yyFlexLexer
    {
    public:
        yy::location location;

        lexer(std::istream& arg_yyin)
            : yyFlexLexer(&arg_yyin)
        {
        }

        yy::parser::symbol_type lex(elna::source::driver& driver);
    };

    }
}

%define api.token.raw
%define api.token.constructor
%define api.value.type variant

%parse-param {elna::source::lexer& lexer}
%param {elna::source::driver& driver}
%locations

%header

%code {
    #define yylex lexer.lex
}
%start program;

%token <std::string> IDENTIFIER "identifier"
%token <std::int32_t> INTEGER "integer"
%token <float> FLOAT "float"
%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 BEGIN_BLOCK END_BLOCK
%token LEFT_PAREN RIGHT_PAREN LEFT_SQUARE RIGHT_SQUARE SEMICOLON DOT COMMA
%token GREATER_EQUAL LESS_EQUAL LESS_THAN GREATER_THAN NOT_EQUAL EQUALS
%token PLUS MINUS MULTIPLICATION DIVISION
%token ASSIGNMENT COLON HAT AT

%precedence THEN
%precedence ELSE

%type <elna::source::number_literal<std::int32_t> *> integer_literal;
%type <elna::source::number_literal<double> *> float_literal;
%type <elna::source::number_literal<bool> *> boolean_literal;
%type <elna::source::char_literal *> character_literal;
%type <elna::source::string_literal *> string_literal;
%type <elna::source::constant_definition *> constant_definition;
%type <std::vector<elna::source::constant_definition *>> constant_part constant_definitions;
%type <elna::source::declaration *> variable_declaration;
%type <std::vector<elna::source::declaration *>> variable_declarations variable_part
    formal_parameter_list;
%type <elna::source::type_expression *> type_expression;
%type <elna::source::expression *> expression pointer summand factor comparand;
%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;
%type <elna::source::if_statement *> if_statement;
%type <elna::source::statement *> statement;
%type <std::vector<elna::source::statement *>> statements optional_statements;
%type <elna::source::procedure_definition *> procedure_definition;
%type <std::vector<elna::source::procedure_definition *>> procedure_definitions procedure_part;
%type <elna::source::type_definition *> type_definition;
%type <std::vector<elna::source::type_definition *>> type_definitions type_part;
%type <elna::source::block *> block;
%%
program:
    type_part constant_part procedure_part variable_part compound_statement DOT
        {
            std::vector<elna::source::definition *> definitions($1.size() + $2.size() + $3.size());
            std::vector<elna::source::definition *>::iterator definition = definitions.begin();

            for (auto& type : $1)
            {
                *definition++ = type;
            }
            for (auto& constant : $2)
            {
                *definition++ = constant;
            }
            for (auto& procedure : $3)
            {
                *definition++ = procedure;
            }
            driver.tree = std::make_unique<elna::source::program>(elna::source::position{},
                 std::move(definitions), std::move($4), std::move($5));
        }
block: constant_part variable_part statement
        {
            std::vector<elna::source::definition *> definitions($1.size());
            std::vector<elna::source::definition *>::iterator definition = definitions.begin();

            for (auto& constant : $1)
            {
                *definition++ = constant;
            }
            $$ = new elna::source::block(elna::source::position{},
                 std::move(definitions), std::move($2), std::move($3));
        };
procedure_definition:
    PROCEDURE IDENTIFIER formal_parameter_list SEMICOLON block SEMICOLON
        {
            $$ = new elna::source::procedure_definition(elna::source::position{},
                 std::move($2), $5);
            std::swap($$->parameters(), $3);
        };
procedure_definitions:
    procedure_definition procedure_definitions
        {
            std::swap($$, $2);
            $$.emplace($$.cbegin(), std::move($1));
        }
    | procedure_definition { $$.emplace_back(std::move($1)); }
procedure_part:
    /* no procedure definitions */ {}
    | procedure_definitions { std::swap($$, $1); }
integer_literal: INTEGER
        {
            $$ = new elna::source::number_literal<std::int32_t>(elna::source::make_position(@1), $1); 
        };
float_literal: FLOAT
        {
            $$ = new elna::source::number_literal<double>(elna::source::make_position(@1), $1); 
        };
character_literal: CHARACTER
        {
            $$ = new elna::source::char_literal(elna::source::make_position(@1), $1.at(0)); 
        };
string_literal: STRING
        {
            $$ = new elna::source::string_literal(elna::source::make_position(@1), $1); 
        };
boolean_literal: BOOLEAN
        {
            $$ = new elna::source::number_literal<bool>(elna::source::make_position(@1), $1); 
        };
compound_statement: BEGIN_BLOCK optional_statements END_BLOCK
        {
            $$ = 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);
        }
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
        {
            $$ = new elna::source::while_statement(elna::source::make_position(@1),
                $2, $4);
        }
if_statement:
    IF expression THEN statement
        {
            $$ = new elna::source::if_statement(elna::source::make_position(@1),
                $2, $4);
        }
    | IF expression THEN statement ELSE statement
        {
            $$ = new elna::source::if_statement(elna::source::make_position(@1),
                $2, $4, $6);
        }
pointer:
    integer_literal { $$ = $1; }
    | float_literal { $$ = $1; }
    | boolean_literal { $$ = $1; }
    | character_literal { $$ = $1; }
    | string_literal { $$ = $1; }
    | designator_expression { $$ = $1; }
    | LEFT_PAREN expression RIGHT_PAREN { $$ = std::move($2); }
summand:
    factor { $$ = std::move($1); }
    | factor MULTIPLICATION factor
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, '*');
        }
    | factor DIVISION factor
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, '/');
        }
factor:
    AT pointer
        {
            $$ = new elna::source::unary_expression(elna::source::make_position(@1),
                $2, '@');
        }
    | pointer { $$ = $1; }
comparand:
    summand PLUS summand
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, '+');
        }
    | summand MINUS summand
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, '-');
        }
    | summand { $$ = std::move($1); }
expression:
    comparand EQUALS comparand
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, '=');
        }
    | comparand NOT_EQUAL comparand
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, 'n');
        }
    | comparand LESS_THAN comparand
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, '<');
        }
    | comparand GREATER_THAN comparand
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, '>');
        }
    | comparand LESS_EQUAL comparand
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, '<');
        }
    | comparand GREATER_EQUAL comparand
        {
            $$ = new elna::source::binary_expression(elna::source::make_position(@1),
                $1, $3, '>');
        }
    | comparand { $$ = std::move($1); }
expressions:
    expression COMMA expressions
        {
            std::swap($$, $3);
            $$.emplace($$.cbegin(), $1);
        }
    | expression { $$.emplace_back(std::move($1)); }
designator_expression:
	designator_expression LEFT_SQUARE expression RIGHT_SQUARE
        {
            $$ = new elna::source::array_access_expression(elna::source::make_position(@1), $1, $3);
        }
    | designator_expression DOT IDENTIFIER
        {
            $$ = new elna::source::field_access_expression(elna::source::make_position(@1), $1, $3);
        }
    | designator_expression HAT
        {
            $$ = new elna::source::dereference_expression(elna::source::make_position(@1), $1);
        }
    | IDENTIFIER
        {
            $$ = new elna::source::variable_expression(elna::source::make_position(@1), $1);
        }
statement:
    compound_statement { $$ = $1; }
    | assign_statement { $$ = $1; }
    | call_statement { $$ = $1; }
    | while_statement { $$ = $1; }
    | if_statement { $$ = $1; }
statements:
    statement SEMICOLON statements
        {
            std::swap($$, $3);
            $$.emplace($$.cbegin(), std::move($1));
        }
    | statement { $$.emplace_back($1); }
optional_statements:
    statements { std::swap($$, $1); }
    | /* no statements */ {}
type_expression:
    ARRAY INTEGER OF type_expression
        {
            $$ = new elna::source::array_type_expression(elna::source::make_position(@1), $4, $2);
        }
    | HAT type_expression
        {
            $$ = new elna::source::pointer_type_expression(elna::source::make_position(@1), $2);
        }
    | IDENTIFIER
        {
            $$ = new elna::source::basic_type_expression(elna::source::make_position(@1), $1);
        }
variable_declaration: IDENTIFIER COLON type_expression
        {
            $$ = new elna::source::declaration(elna::source::make_position(@1), $1, $3); 
        };
variable_declarations:
    variable_declaration COMMA variable_declarations
        {
            std::swap($$, $3);
            $$.emplace($$.cbegin(), $1);
        }
    | variable_declaration { $$.emplace_back(std::move($1)); }
variable_part:
    /* no variable declarations */ {}
    | VAR variable_declarations SEMICOLON { std::swap($$, $2); }
constant_definition: IDENTIFIER EQUALS integer_literal
        {
            $$ = new elna::source::constant_definition(elna::source::make_position(@1), $1, $3); 
        }
constant_definitions:
    constant_definition COMMA constant_definitions
        {
            std::swap($$, $3);
            $$.emplace($$.cbegin(), std::move($1));
        }
    | constant_definition { $$.emplace_back(std::move($1)); }
constant_part:
    /* no constant definitions */ {}
    | CONST constant_definitions SEMICOLON { std::swap($$, $2); }
type_definition: IDENTIFIER EQUALS type_expression
        {
            $$ = new elna::source::type_definition(elna::source::make_position(@1), $1, $3);
        }
type_definitions:
    type_definition COMMA type_definitions
        {
            std::swap($$, $3);
            $$.emplace($$.cbegin(), std::move($1));
        }
    | type_definition { $$.emplace_back(std::move($1)); }
type_part:
    /* no type definitions */ {}
    | TYPE type_definitions SEMICOLON { std::swap($$, $2); }
formal_parameter_list:
    LEFT_PAREN RIGHT_PAREN {}
    | LEFT_PAREN variable_declarations RIGHT_PAREN { std::swap($$, $2); }
actual_parameter_list:
    LEFT_PAREN RIGHT_PAREN {}
    | LEFT_PAREN expressions RIGHT_PAREN { std::swap($$, $2); }
%%

void yy::parser::error(const location_type& loc, const std::string& message)
{
    driver.error(loc, message);
}