/* * matiec - a compiler for the programming languages defined in IEC 61131-3 * Copyright (C) 2003-2011 Mario de Sousa (msousa@fe.up.pt) * Copyright (C) 2007-2011 Laurent Bessard and Edouard Tisserant * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . * * * This code is made available on the understanding that it will not be * used in safety-critical situations without a full and competent review. */ /* * An IEC 61131-3 compiler. * * Based on the * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10) * */ /* * Definition of the Abstract Syntax data structure components */ /* * ABSYNTAX.DEF * * This generates the parse tree structure used to bind the components * identified by Bison in the correct syntax order. At the end of the * Bison analysis the tree is walked in a sequential fashion generating * the relavent code. */ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /* */ /* safe Symbols are defined in: */ /* PLCopen - Technical Committee 5 */ /* Safety Software Technical Specification, */ /* Part 1: Concepts and Function Blocks, */ /* Version 1.0 – Official Release - 2006-01-31 */ /* */ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /* */ /* Symbols defined in: */ /* FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10) */ /* */ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /*****************************************************************/ /* Based on the */ /* FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10) */ /* EN/ENO */ /* NOTE we store 'EN' and 'ENO' tokens in an identifier_c * as they may be used as variables, and it is much easier * to handle them (fewer special cases) if we do it that way... */ /* SYM_REF0(en_param_c) SYM_REF0(eno_param_c) */ /* A class used to identify an entry (literal, variable, etc...) in the abstract syntax tree with an invalid data type */ /* This is only used from stage3 onwards. Stages 1 and 2 will never create any instances of invalid_type_name_c */ SYM_REF0(invalid_type_name_c) /********************/ /* 2.1.6 - Pragmas */ /********************/ SYM_REF0(disable_code_generation_pragma_c) SYM_REF0(enable_code_generation_pragma_c) SYM_TOKEN(pragma_c) /***************************/ /* B 0 - Programming Model */ /***************************/ /* enumvalue_symtable is filled in by enum_declaration_check_c, during stage3 semantic verification, with a list of all enumerated constants declared inside this POU */ SYM_LIST(library_c, enumvalue_symtable_t enumvalue_symtable;) /*************************/ /* B.1 - Common elements */ /*************************/ /*******************************************/ /* B 1.1 - Letters, digits and identifiers */ /*******************************************/ SYM_TOKEN(identifier_c) /* A special identifier class, used for identifiers that have been previously declared as a derived datatype */ /* This is currently needed because generate_c stage 4 needs to handle the array datatype identifiers differently to all other identifiers. */ SYM_TOKEN(derived_datatype_identifier_c) SYM_TOKEN(poutype_identifier_c) /*********************/ /* B 1.2 - Constants */ /*********************/ /*********************************/ /* B 1.2.XX - Reference Literals */ /*********************************/ /* defined in IEC 61131-3 v3 - Basically the 'NULL' keyword! */ SYM_REF0(ref_value_null_literal_c) /******************************/ /* B 1.2.1 - Numeric Literals */ /******************************/ SYM_TOKEN(real_c) SYM_TOKEN(integer_c) SYM_TOKEN(binary_integer_c) SYM_TOKEN(octal_integer_c) SYM_TOKEN(hex_integer_c) /* Note: * We do not have signed_integer_c and signed_real_c classes. * These are stored in the parse tree as a integer_c or real_c * preceded by a unary minus operator if they are inside an expression, * or a neg_integer_c and neg_real_c when used outside an ST expression. */ /* Not required: SYM_TOKEN(signed_integer_c) SYM_TOKEN(signed_real_c) */ /* NOTE: literal __values__ are stored directly in classes such as: * - real_c * - integer_c * - binary_integer_c * - etc... * * However, for both the real_c and the integer_c, if they are preceded * by a '-' negation sign, they are further encapsulated inside * a neg_literal_c (i.e. the neg_literal_c will point to the * real_c or integer_c with the value being negated. * neg_literal_c -> integer_literal_c * OR * neg_literal_c -> real_literal_c * * However, this has since been changed to... * - replace the neg_literal_c with two distinc classes * (neg_integer_c and neg_real_c), one for each * lietral type. * * This change was done in order to ease the writing of semantic verification (stage3) code. * However, that version of the code has since been replaced by a newer and better algoritm. * This means the above change can now be undone, but there is really no need to undo it, * so we leave it as it is. */ SYM_REF1(neg_real_c, exp) SYM_REF1(neg_integer_c, exp) /* Not required: SYM_REF2(numeric_literal_c, type, value) */ SYM_REF2(integer_literal_c, type, value) SYM_REF2(real_literal_c, type, value) SYM_REF2(bit_string_literal_c, type, value) /* A typed or untyped boolean literal... */ /* type may be NULL */ SYM_REF2(boolean_literal_c, type, value) /* helper class for boolean_literal_c */ SYM_REF0(boolean_true_c) /* helper class for boolean_literal_c */ SYM_REF0(boolean_false_c) /*******************************/ /* B.1.2.2 Character Strings */ /*******************************/ SYM_TOKEN(double_byte_character_string_c) SYM_TOKEN(single_byte_character_string_c) /***************************/ /* B 1.2.3 - Time Literals */ /***************************/ /************************/ /* B 1.2.3.1 - Duration */ /************************/ SYM_REF0(neg_time_c) SYM_REF3(duration_c, type_name, neg, interval) SYM_REF5(interval_c, days, hours, minutes, seconds, milliseconds) SYM_TOKEN(fixed_point_c) /* SYM_REF2(days_c, days, hours) SYM_REF2(hours_c, hours, minutes) SYM_REF2(minutes_c, minutes, seconds) SYM_REF2(seconds_c, seconds, milliseconds) SYM_REF1(milliseconds_c, milliseconds) */ /************************************/ /* B 1.2.3.2 - Time of day and Date */ /************************************/ SYM_REF2(time_of_day_c, type_name, daytime) SYM_REF3(daytime_c, day_hour, day_minute, day_second) SYM_REF2(date_c, type_name, date_literal) SYM_REF3(date_literal_c, year, month, day) SYM_REF3(date_and_time_c, type_name, date_literal, daytime) /**********************/ /* B.1.3 - Data types */ /**********************/ /***********************************/ /* B 1.3.1 - Elementary Data Types */ /***********************************/ SYM_REF0(time_type_name_c) SYM_REF0(bool_type_name_c) SYM_REF0(sint_type_name_c) SYM_REF0(int_type_name_c) SYM_REF0(dint_type_name_c) SYM_REF0(lint_type_name_c) SYM_REF0(usint_type_name_c) SYM_REF0(uint_type_name_c) SYM_REF0(udint_type_name_c) SYM_REF0(ulint_type_name_c) SYM_REF0(real_type_name_c) SYM_REF0(lreal_type_name_c) SYM_REF0(date_type_name_c) SYM_REF0(tod_type_name_c) SYM_REF0(dt_type_name_c) SYM_REF0(byte_type_name_c) SYM_REF0(word_type_name_c) SYM_REF0(dword_type_name_c) SYM_REF0(lword_type_name_c) SYM_REF0(string_type_name_c) SYM_REF0(wstring_type_name_c) SYM_REF0(void_type_name_c) /* a non-standard extension! */ /*****************************************************************/ /* Keywords defined in "Safety Software Technical Specification" */ /*****************************************************************/ SYM_REF0(safetime_type_name_c) SYM_REF0(safebool_type_name_c) SYM_REF0(safesint_type_name_c) SYM_REF0(safeint_type_name_c) SYM_REF0(safedint_type_name_c) SYM_REF0(safelint_type_name_c) SYM_REF0(safeusint_type_name_c) SYM_REF0(safeuint_type_name_c) SYM_REF0(safeudint_type_name_c) SYM_REF0(safeulint_type_name_c) SYM_REF0(safereal_type_name_c) SYM_REF0(safelreal_type_name_c) SYM_REF0(safedate_type_name_c) SYM_REF0(safetod_type_name_c) SYM_REF0(safedt_type_name_c) SYM_REF0(safebyte_type_name_c) SYM_REF0(safeword_type_name_c) SYM_REF0(safedword_type_name_c) SYM_REF0(safelword_type_name_c) SYM_REF0(safestring_type_name_c) SYM_REF0(safewstring_type_name_c) /********************************/ /* B.1.3.2 - Generic data types */ /********************************/ /* ANY is currently only allowed when defining REF_TO ANY datatypes * (equivalent to a (void *)). This is a non standard extension to the * standard. * Standard library function that use the generic datatypes (ANY_***) are * currently handed as overloaded functions, and do not therefore require * the use of the generic datatype keywords. */ SYM_REF0(generic_type_any_c) // ANY /* SYM_REF0(generic_type_any_derived_c) // ANY_DERIVED SYM_REF0(generic_type_any_elementary_c) // ANY_ELEMENTARY SYM_REF0(generic_type_any_magnitude_c) // ANY_MAGNITUDE SYM_REF0(generic_type_any_num_c) // ANY_NUM SYM_REF0(generic_type_any_real_c) // ANY_REAL SYM_REF0(generic_type_any_int_c) // ANY_INT SYM_REF0(generic_type_any_bit_c) // ANY_BIT SYM_REF0(generic_type_any_string_c) // ANY_STRING SYM_REF0(generic_type_any_date_c) // ANY_DATE */ /********************************/ /* B 1.3.3 - Derived data types */ /********************************/ /* TYPE type_declaration_list END_TYPE */ SYM_REF1(data_type_declaration_c, type_declaration_list) /* helper symbol for data_type_declaration */ SYM_LIST(type_declaration_list_c) /* simple_type_name ':' simple_spec_init */ SYM_REF2(simple_type_declaration_c, simple_type_name, simple_spec_init) /* simple_specification ASSIGN constant */ SYM_REF2(simple_spec_init_c, simple_specification, constant) /* subrange_type_name ':' subrange_spec_init */ SYM_REF2(subrange_type_declaration_c, subrange_type_name, subrange_spec_init) /* subrange_specification ASSIGN signed_integer */ SYM_REF2(subrange_spec_init_c, subrange_specification, signed_integer) /* integer_type_name '(' subrange')' */ SYM_REF2(subrange_specification_c, integer_type_name, subrange) /* signed_integer DOTDOT signed_integer */ /* dimension will be filled in during stage 3 (array_range_check_c) with the number of elements in this subrange */ SYM_REF2(subrange_c, lower_limit, upper_limit, unsigned long long int dimension;) /* enumerated_type_name ':' enumerated_spec_init */ SYM_REF2(enumerated_type_declaration_c, enumerated_type_name, enumerated_spec_init) /* enumerated_specification ASSIGN enumerated_value */ SYM_REF2(enumerated_spec_init_c, enumerated_specification, enumerated_value) /* helper symbol for enumerated_specification->enumerated_spec_init */ /* enumerated_value_list ',' enumerated_value */ SYM_LIST(enumerated_value_list_c) /* enumerated_type_name '#' identifier */ SYM_REF2(enumerated_value_c, type, value) /* identifier ':' array_spec_init */ SYM_REF2(array_type_declaration_c, identifier, array_spec_init) /* array_specification [ASSIGN array_initialization] */ /* array_initialization may be NULL ! */ SYM_REF2(array_spec_init_c, array_specification, array_initialization) /* ARRAY '[' array_subrange_list ']' OF non_generic_type_name */ SYM_REF2(array_specification_c, array_subrange_list, non_generic_type_name) /* helper symbol for array_specification */ /* array_subrange_list ',' subrange */ SYM_LIST(array_subrange_list_c) /* array_initialization: '[' array_initial_elements_list ']' */ /* helper symbol for array_initialization */ /* array_initial_elements_list ',' array_initial_elements */ SYM_LIST(array_initial_elements_list_c) /* integer '(' [array_initial_element] ')' */ /* array_initial_element may be NULL ! */ SYM_REF2(array_initial_elements_c, integer, array_initial_element) /* structure_type_name ':' structure_specification */ SYM_REF2(structure_type_declaration_c, structure_type_name, structure_specification) /* structure_type_name ASSIGN structure_initialization */ /* structure_initialization may be NULL ! */ SYM_REF2(initialized_structure_c, structure_type_name, structure_initialization) /* helper symbol for structure_declaration */ /* structure_declaration: STRUCT structure_element_declaration_list END_STRUCT */ /* structure_element_declaration_list structure_element_declaration ';' */ SYM_LIST(structure_element_declaration_list_c) /* structure_element_name ':' *_spec_init */ SYM_REF2(structure_element_declaration_c, structure_element_name, spec_init) /* helper symbol for structure_initialization */ /* structure_initialization: '(' structure_element_initialization_list ')' */ /* structure_element_initialization_list ',' structure_element_initialization */ SYM_LIST(structure_element_initialization_list_c) /* structure_element_name ASSIGN value */ SYM_REF2(structure_element_initialization_c, structure_element_name, value) /* string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */ /* * NOTE: * (Summary: Contrary to what is expected, the * string_type_declaration_c is not used to store * simple string type declarations that do not include * size limits. * For e.g.: * str1_type: STRING := "hello!" * will be stored in a simple_type_declaration_c * instead of a string_type_declaration_c. * The following: * str2_type: STRING [64] := "hello!" * will be stored in a sring_type_declaration_c * * Read on for why this is done... * End Summary) * * According to the spec, the valid construct * TYPE new_str_type : STRING := "hello!"; END_TYPE * has two possible routes to type_declaration... * * Route 1: * type_declaration: single_element_type_declaration * single_element_type_declaration: simple_type_declaration * simple_type_declaration: identifier ':' simple_spec_init * simple_spec_init: simple_specification ASSIGN constant * (shift: identifier <- 'new_str_type') * simple_specification: elementary_type_name * elementary_type_name: STRING * (shift: elementary_type_name <- STRING) * (reduce: simple_specification <- elementary_type_name) * (shift: constant <- "hello!") * (reduce: simple_spec_init: simple_specification ASSIGN constant) * (reduce: ...) * * * Route 2: * type_declaration: string_type_declaration * string_type_declaration: identifier ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init * (shift: identifier <- 'new_str_type') * elementary_string_type_name: STRING * (shift: elementary_string_type_name <- STRING) * (shift: string_type_declaration_size <- empty ) * string_type_declaration_init: ASSIGN character_string * (shift: character_string <- "hello!") * (reduce: string_type_declaration_init <- ASSIGN character_string) * (reduce: string_type_declaration <- identifier ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init ) * (reduce: type_declaration <- string_type_declaration) * * * At first glance it seems that removing route 1 would make * the most sense. Unfortunately the construct 'simple_spec_init' * shows up multiple times in other rules, so changing this construct * would also mean changing all the rules in which it appears. * I (Mario) therefore chose to remove route 2 instead. This means * that the above declaration gets stored in a * simple_type_declaration_c, and not in a string_type_declaration_c * as would be expected! */ /* string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */ SYM_REF4(string_type_declaration_c, string_type_name, elementary_string_type_name, string_type_declaration_size, string_type_declaration_init) /* may be == NULL! */ /* helper symbol for fb_name_decl_c */ /* This symbol/leaf does not exist in the IEC standard syntax as an isolated symbol, * as, for some reason, the standard syntax defines FB variable declarations in a slightly * different style as all other spec_init declarations. I.e., fr FBs variable declarations, * the standard defines a single leaf/node (fb_name_decl) that references: * a) the variable name list * b) the FB datatype * c) the FB intial value * * All other variable declarations break this out into two nodes: * 1) references b) and c) above (usually named ***_spec_init) * 2) references a), and node 1) * * In order to allow the datatype analyses to proceed without special cases, we will handle * FB variable declarations in the same style. For this reason, we have added the * following node to the Abstract Syntax Tree, even though it does not have a direct equivalent in * the standard syntax. */ /* function_block_type_name ASSIGN structure_initialization */ /* structure_initialization -> may be NULL ! */ SYM_REF2(fb_spec_init_c, function_block_type_name, structure_initialization) /* Taken fron IEC 61131-3 v3 * // Table 14 - Reference operations * Ref_Type_Decl : Ref_Type_Name ':' Ref_Spec_Init ; * Ref_Spec_Init : Ref_Spec ( ':=' Ref_Value )? ; * Ref_Spec : 'REF_TO' Non_Gen_Type_Name ; * Ref_Type_Name : Identifier ; * Ref_Name : Identifier ; * Ref_Value : Ref_Addr | 'NULL' ; * Ref_Addr : 'REF' '(' (Symbolic_Variable | FB_Name | Class_Instance_Name ) ')' ; * Ref_Assign : Ref_Name ':=' (Ref_Name | Ref_Deref | Ref_Value ) ; * Ref_Deref : 'DREF' '(' Ref_Name ')' ; */ /* REF_TO (non_generic_type_name | function_block_type_name) */ SYM_REF1(ref_spec_c, type_name) /* ref_spec [ ASSIGN ref_initialization ]; */ /* NOTE: ref_initialization may be NULL!! */ SYM_REF2(ref_spec_init_c, ref_spec, ref_initialization) /* identifier ':' ref_spec_init */ SYM_REF2(ref_type_decl_c, ref_type_name, ref_spec_init) /*********************/ /* B 1.4 - Variables */ /*********************/ SYM_REF1(symbolic_variable_c, var_name) /* symbolic_constant_c is used only when a variable is used inside the subrange of an array declaration * e.g.: ARRAY [1 .. maxval] OF INT * where maxval is a CONSTANT variable. * When maxval shows up in the POU body, it will be stored as a standard symbolic_variable_c in the AST. * When maxval shows up in the ARRAY declaration, it will be stored as a symbolic_constant_c in the AST. * This will allow us to more easily handle this special case, without affecting the remaining working code. */ SYM_REF1(symbolic_constant_c, var_name) // a non-standard extension!! /********************************************/ /* B.1.4.1 Directly Represented Variables */ /********************************************/ SYM_TOKEN(direct_variable_c) /*************************************/ /* B.1.4.2 Multi-element Variables */ /*************************************/ /* subscripted_variable '[' subscript_list ']' */ SYM_REF2(array_variable_c, subscripted_variable, subscript_list) /* subscript_list ',' subscript */ SYM_LIST(subscript_list_c) /* record_variable '.' field_selector */ /* WARNING: input and/or output variables of function blocks * may be accessed as fields of a structured variable! * Code handling a structured_variable_c must take this into account! * (i.e. that a FB instance may be accessed as a structured variable)! * * WARNING: Status bit (.X) and activation time (.T) of STEPS in SFC diagrams * may be accessed as fields of a structured variable! * Code handling a structured_variable_c must take this into account * (i.e. that an SFC STEP may be accessed as a structured variable)! */ SYM_REF2(structured_variable_c, record_variable, field_selector) /******************************************/ /* B 1.4.3 - Declaration & Initialisation */ /******************************************/ SYM_REF0(constant_option_c) SYM_REF0(retain_option_c) SYM_REF0(non_retain_option_c) /* VAR_INPUT [option] input_declaration_list END_VAR */ /* option -> the RETAIN/NON_RETAIN/ directive... */ /* NOTE: We need to implicitly define the EN and ENO function and FB parameters when the user * does not do it explicitly in the IEC 61131-3 source code. * To be able to distinguish later on between implictly and explicitly defined * variables, we use the 'method' flag that allows us to remember * whether this declaration was in the original source code (method -> implicit_definition_c) * or not (method -> explicit_definition_c). */ SYM_REF3(input_declarations_c, option, input_declaration_list, method) /* helper symbol for input_declarations */ SYM_LIST(input_declaration_list_c) /* NOTE: The formal definition of the standard is erroneous, as it simply does not * consider the EN and ENO keywords! * The semantic description of the languages clearly states that these may be * used in several ways. One of them is to declare an EN input parameter, or * an ENO output parameter. * We have added the 'en_param_declaration_c' and 'eno_param_declaration_c' * to cover for this. * * We could have re-used the standard class used for all other input variables (with * an identifier set to 'EN' or 'ENO') however we may sometimes need to add this * declaration implicitly (if the user does not include it in the source * code himself), and it is good to know whether it was added implicitly or not. * So we create a new class that has a 'method' flag that allows us to remember * whether this declaration was in the original source code (method -> implicit_definition_c) * or not (method -> explicit_definition_c). */ SYM_REF0(implicit_definition_c) SYM_REF0(explicit_definition_c) /* type_decl is a simple_spec_init_c */ SYM_REF3(en_param_declaration_c, name, type_decl, method) SYM_REF3(eno_param_declaration_c, name, type, method) /* edge -> The F_EDGE or R_EDGE directive */ SYM_REF2(edge_declaration_c, edge, var1_list) SYM_REF0(raising_edge_option_c) SYM_REF0(falling_edge_option_c) /* spec_init is one of the following... * simple_spec_init_c * * subrange_spec_init_c * * enumerated_spec_init_c * */ SYM_REF2(var1_init_decl_c, var1_list, spec_init) /* | var1_list ',' variable_name */ SYM_LIST(var1_list_c) /* | [var1_list ','] variable_name integer '..' */ /* NOTE: This is an extension to the standard!!! */ /* In order to be able to handle extensible standard functions * (i.e. standard functions that may have a variable number of * input parameters, such as AND(word#33, word#44, word#55, word#66), * we have extended the acceptable syntax to allow var_name '..' * in an input variable declaration. * * This allows us to parse the declaration of standard * extensible functions and load their interface definition * into the abstract syntax tree just like we do to other * user defined functions. * This has the advantage that we can later do semantic * checking of calls to functions (be it a standard or user defined * function) in (almost) exactly the same way. * * The integer tells the compiler the number of the first parameter. * for example, for ADD(IN1 := 11, IN2:=22), the index for IN starts off at 1. * Some other standard library functions, such as MUX, has the extensible * variable starting off from 0 (IN0, IN1, IN2, ...). * * Of course, we have a flag that disables this syntax when parsing user * written code, so we only allow this extra syntax while parsing the * 'header' file that declares all the standard IEC 61131-3 functions. */ SYM_REF2(extensible_input_parameter_c, var_name, first_index) /* var1_list ':' array_spec_init */ SYM_REF2(array_var_init_decl_c, var1_list, array_spec_init) /* var1_list ':' initialized_structure */ SYM_REF2(structured_var_init_decl_c, var1_list, initialized_structure) /* fb_name_list ':' function_block_type_name ASSIGN structure_initialization */ /* NOTE: in order to allow datatype handling to proceed using the normal algorithm with no special cases, * we will be storing the * function_block_type_name ASSIGN structure_initialization * componentes inside a new node, namely fb_spec_init_c */ /* structure_initialization -> may be NULL ! */ SYM_REF2(fb_name_decl_c, fb_name_list, fb_spec_init) /* fb_name_list ',' fb_name */ SYM_LIST(fb_name_list_c) /* VAR_OUTPUT [RETAIN | NON_RETAIN] var_init_decl_list END_VAR */ /* option -> may be NULL ! */ /* NOTE: We need to implicitly define the EN and ENO function and FB parameters when the user * does not do it explicitly in the IEC 61131-3 source code. * To be able to distinguish later on between implictly and explicitly defined * variables, we use the 'method' flag that allows us to remember * whether this declaration was in the original source code (method -> implicit_definition_c) * or not (method -> explicit_definition_c). */ SYM_REF3(output_declarations_c, option, var_init_decl_list, method) /* VAR_IN_OUT var_declaration_list END_VAR */ SYM_REF1(input_output_declarations_c, var_declaration_list) /* helper symbol for input_output_declarations */ /* var_declaration_list var_declaration ';' */ SYM_LIST(var_declaration_list_c) /* var1_list ':' array_specification */ SYM_REF2(array_var_declaration_c, var1_list, array_specification) /* var1_list ':' structure_type_name */ SYM_REF2(structured_var_declaration_c, var1_list, structure_type_name) /* VAR [CONSTANT] var_init_decl_list END_VAR */ /* option -> may be NULL ! */ SYM_REF2(var_declarations_c, option, var_init_decl_list) /* VAR RETAIN var_init_decl_list END_VAR */ SYM_REF1(retentive_var_declarations_c, var_init_decl_list) /* VAR [CONSTANT|RETAIN|NON_RETAIN] located_var_decl_list END_VAR */ /* option -> may be NULL ! */ SYM_REF2(located_var_declarations_c, option, located_var_decl_list) /* helper symbol for located_var_declarations */ /* located_var_decl_list located_var_decl ';' */ SYM_LIST(located_var_decl_list_c) /* [variable_name] location ':' located_var_spec_init */ /* variable_name -> may be NULL ! */ SYM_REF3(located_var_decl_c, variable_name, location, located_var_spec_init) /*| VAR_EXTERNAL [CONSTANT] external_declaration_list END_VAR */ /* option -> may be NULL ! */ SYM_REF2(external_var_declarations_c, option, external_declaration_list) /* helper symbol for external_var_declarations */ /*| external_declaration_list external_declaration';' */ SYM_LIST(external_declaration_list_c) /* global_var_name ':' (simple_specification|subrange_specification|enumerated_specification|array_specification|prev_declared_structure_type_name|function_block_type_name */ SYM_REF2(external_declaration_c, global_var_name, specification) /*| VAR_GLOBAL [CONSTANT|RETAIN] global_var_decl_list END_VAR */ /* option -> may be NULL ! */ SYM_REF2(global_var_declarations_c, option, global_var_decl_list) /* helper symbol for global_var_declarations */ /*| global_var_decl_list global_var_decl ';' */ SYM_LIST(global_var_decl_list_c) /*| global_var_spec ':' [located_var_spec_init|function_block_type_name] */ /* type_specification ->may be NULL ! */ SYM_REF2(global_var_decl_c, global_var_spec, type_specification) /*| global_var_name location */ SYM_REF2(global_var_spec_c, global_var_name, location) /* AT direct_variable */ SYM_REF1(location_c, direct_variable) /*| global_var_list ',' global_var_name */ SYM_LIST(global_var_list_c) /* var1_list ':' single_byte_string_spec */ SYM_REF2(single_byte_string_var_declaration_c, var1_list, single_byte_string_spec) /* STRING ['[' integer ']'] [ASSIGN single_byte_character_string] */ /* integer ->may be NULL ! */ /* single_byte_character_string ->may be NULL ! */ SYM_REF2(single_byte_string_spec_c, string_spec, single_byte_character_string) /* STRING ['[' integer ']'] */ /* integer ->may be NULL ! */ SYM_REF2(single_byte_limited_len_string_spec_c, string_type_name, character_string_len) /* WSTRING ['[' integer ']'] */ /* integer ->may be NULL ! */ SYM_REF2(double_byte_limited_len_string_spec_c, string_type_name, character_string_len) /* var1_list ':' double_byte_string_spec */ SYM_REF2(double_byte_string_var_declaration_c, var1_list, double_byte_string_spec) /* WSTRING ['[' integer ']'] [ASSIGN double_byte_character_string] */ /* integer ->may be NULL ! */ /* double_byte_character_string ->may be NULL ! */ SYM_REF2(double_byte_string_spec_c, string_spec, double_byte_character_string) /*| VAR [RETAIN|NON_RETAIN] incompl_located_var_decl_list END_VAR */ /* option ->may be NULL ! */ SYM_REF2(incompl_located_var_declarations_c, option, incompl_located_var_decl_list) /* helper symbol for incompl_located_var_declarations */ /*| incompl_located_var_decl_list incompl_located_var_decl ';' */ SYM_LIST(incompl_located_var_decl_list_c) /* variable_name incompl_location ':' var_spec */ SYM_REF3(incompl_located_var_decl_c, variable_name, incompl_location, var_spec) /* AT incompl_location_token */ SYM_TOKEN(incompl_location_c) /* intermediate helper symbol for: * - non_retentive_var_decls * - output_declarations */ SYM_LIST(var_init_decl_list_c) /**************************************/ /* B.1.5 - Program organization units */ /**************************************/ /***********************/ /* B 1.5.1 - Functions */ /***********************/ /* enumvalue_symtable is filled in by enum_declaration_check_c, during stage3 semantic verification, with a list of all enumerated constants declared inside this POU */ SYM_REF4(function_declaration_c, derived_function_name, type_name, var_declarations_list, function_body, enumvalue_symtable_t enumvalue_symtable;) /* intermediate helper symbol for * - function_declaration * - function_block_declaration * - program_declaration */ SYM_LIST(var_declarations_list_c) /* option -> storage method, CONSTANT or */ SYM_REF2(function_var_decls_c, option, decl_list) /* intermediate helper symbol for function_var_decls */ SYM_LIST(var2_init_decl_list_c) /*****************************/ /* B 1.5.2 - Function Blocks */ /*****************************/ /* FUNCTION_BLOCK derived_function_block_name io_OR_other_var_declarations function_block_body END_FUNCTION_BLOCK */ /* enumvalue_symtable is filled in by enum_declaration_check_c, during stage3 semantic verification, with a list of all enumerated constants declared inside this POU */ SYM_REF3(function_block_declaration_c, fblock_name, var_declarations, fblock_body, enumvalue_symtable_t enumvalue_symtable;) /* intermediate helper symbol for function_declaration */ /* { io_var_declarations | other_var_declarations } */ /* * NOTE: we re-use the var_declarations_list_c */ /* VAR_TEMP temp_var_decl_list END_VAR */ SYM_REF1(temp_var_decls_c, var_decl_list) /* intermediate helper symbol for temp_var_decls */ SYM_LIST(temp_var_decls_list_c) /* VAR NON_RETAIN var_init_decl_list END_VAR */ SYM_REF1(non_retentive_var_decls_c, var_decl_list) /**********************/ /* B 1.5.3 - Programs */ /**********************/ /* PROGRAM program_type_name program_var_declarations_list function_block_body END_PROGRAM */ /* enumvalue_symtable is filled in by enum_declaration_check_c, during stage3 semantic verification, with a list of all enumerated constants declared inside this POU */ SYM_REF3(program_declaration_c, program_type_name, var_declarations, function_block_body, enumvalue_symtable_t enumvalue_symtable;) /* intermediate helper symbol for program_declaration_c */ /* { io_var_declarations | other_var_declarations } */ /* * NOTE: we re-use the var_declarations_list_c */ /*********************************************/ /* B.1.6 Sequential function chart elements */ /*********************************************/ /* | sequential_function_chart sfc_network */ SYM_LIST(sequential_function_chart_c) /* initial_step {step | transition | action} */ SYM_LIST(sfc_network_c) /* INITIAL_STEP step_name ':' action_association_list END_STEP */ SYM_REF2(initial_step_c, step_name, action_association_list) /* | action_association_list action_association ';' */ SYM_LIST(action_association_list_c) /* STEP step_name ':' action_association_list END_STEP */ SYM_REF2(step_c, step_name, action_association_list) /* action_name '(' action_qualifier indicator_name_list ')' */ /* action_qualifier -> may be NULL ! */ SYM_REF3(action_association_c, action_name, action_qualifier, indicator_name_list) /* N | R | S | P */ SYM_TOKEN(qualifier_c) /* L | D | SD | DS | SL */ SYM_TOKEN(timed_qualifier_c) /* | indicator_name_list ',' indicator_name */ SYM_LIST(indicator_name_list_c) /* qualifier | timed_qualifier ',' action_time */ /* action_time -> may be NULL ! */ SYM_REF2(action_qualifier_c, action_qualifier, action_time) /* TRANSITION [transition_name] ['(' PRIORITY ASSIGN integer ')'] * FROM steps TO steps * transition_condition * END_TRANSITION */ /* transition_name -> may be NULL ! */ /* integer -> may be NULL ! */ SYM_REF5(transition_c, transition_name, integer, from_steps, to_steps, transition_condition) /* ':' eol_list simple_instr_list | ASSIGN expression ';' */ /* transition_condition_il -> may be NULL ! */ /* transition_condition_st -> may be NULL ! */ SYM_REF2(transition_condition_c, transition_condition_il, transition_condition_st) /* step_name | '(' step_name_list ')' */ /* step_name -> may be NULL ! */ /* step_name_list -> may be NULL ! */ SYM_REF2(steps_c, step_name, step_name_list) /* | step_name_list ',' step_name */ SYM_LIST(step_name_list_c) /* ACTION action_name ':' function_block_body END_ACTION */ SYM_REF2(action_c, action_name, function_block_body) /********************************/ /* B 1.7 Configuration elements */ /********************************/ /* CONFIGURATION configuration_name optional_global_var_declarations (resource_declaration_list | single_resource_declaration) optional_access_declarations optional_instance_specific_initializations END_CONFIGURATION */ /* enumvalue_symtable is filled in by enum_declaration_check_c, during stage3 semantic verification, with a list of all enumerated constants declared inside this POU */ SYM_REF5(configuration_declaration_c, configuration_name, global_var_declarations, resource_declarations, access_declarations, instance_specific_initializations, enumvalue_symtable_t enumvalue_symtable;) /* intermediate helper symbol for configuration_declaration */ /* { global_var_declarations_list } */ SYM_LIST(global_var_declarations_list_c) /* helper symbol for configuration_declaration */ SYM_LIST(resource_declaration_list_c) /* RESOURCE resource_name ON resource_type_name optional_global_var_declarations single_resource_declaration END_RESOURCE */ /* enumvalue_symtable is filled in by enum_declaration_check_c, during stage3 semantic verification, with a list of all enumerated constants declared inside this POU */ SYM_REF4(resource_declaration_c, resource_name, resource_type_name, global_var_declarations, resource_declaration, enumvalue_symtable_t enumvalue_symtable;) /* task_configuration_list program_configuration_list */ SYM_REF2(single_resource_declaration_c, task_configuration_list, program_configuration_list) /* helper symbol for single_resource_declaration */ SYM_LIST(task_configuration_list_c) /* helper symbol for single_resource_declaration */ SYM_LIST(program_configuration_list_c) /* helper symbol for * - access_path * - instance_specific_init */ SYM_LIST(any_fb_name_list_c) /* [resource_name '.'] global_var_name ['.' structure_element_name] */ SYM_REF3(global_var_reference_c, resource_name, global_var_name, structure_element_name) /* prev_declared_program_name '.' symbolic_variable */ SYM_REF2(program_output_reference_c, program_name, symbolic_variable) /* TASK task_name task_initialization */ SYM_REF2(task_configuration_c, task_name, task_initialization) /* '(' [SINGLE ASSIGN data_source ','] [INTERVAL ASSIGN data_source ','] PRIORITY ASSIGN integer ')' */ SYM_REF3(task_initialization_c, single_data_source, interval_data_source, priority_data_source) /* PROGRAM [RETAIN | NON_RETAIN] program_name [WITH task_name] ':' program_type_name ['(' prog_conf_elements ')'] */ SYM_REF5(program_configuration_c, retain_option, program_name, task_name, program_type_name, prog_conf_elements) /* prog_conf_elements ',' prog_conf_element */ SYM_LIST(prog_conf_elements_c) /* fb_name WITH task_name */ SYM_REF2(fb_task_c, fb_name, task_name) /* any_symbolic_variable ASSIGN prog_data_source */ SYM_REF2(prog_cnxn_assign_c, symbolic_variable, prog_data_source) /* any_symbolic_variable SENDTO data_sink */ SYM_REF2(prog_cnxn_sendto_c, symbolic_variable, data_sink) /* VAR_CONFIG instance_specific_init_list END_VAR */ SYM_REF1(instance_specific_initializations_c, instance_specific_init_list) /* helper symbol for instance_specific_initializations */ SYM_LIST(instance_specific_init_list_c) /* resource_name '.' program_name '.' {fb_name '.'} ((variable_name [location] ':' located_var_spec_init) | (fb_name ':' fb_initialization)) */ SYM_REF6(instance_specific_init_c, resource_name, program_name, any_fb_name_list, variable_name, location, initialization) /* helper symbol for instance_specific_init */ /* function_block_type_name ':=' structure_initialization */ SYM_REF2(fb_initialization_c, function_block_type_name, structure_initialization) /****************************************/ /* B.2 - Language IL (Instruction List) */ /****************************************/ /***********************************/ /* B 2.1 Instructions and Operands */ /***********************************/ /*| instruction_list il_instruction */ SYM_LIST(instruction_list_c) /* | label ':' [il_incomplete_instruction] eol_list */ /* NOTE: The parameters 'prev_il_instruction'/'next_il_instruction' are used to point to all previous/next il instructions that may be executed imedaitely before/after this instruction. * In case of an il instruction preceded by a label, the previous_il_instruction will include all IL instructions that jump to this label! * It is filled in by the flow_control_analysis_c during stage 3. * This will essentially be a doubly linked list of il_instruction_c and il_simple_instruction_c objects!! */ SYM_REF2(il_instruction_c, label, il_instruction, std::vector prev_il_instruction, next_il_instruction;) /* | il_simple_operator [il_operand] */ SYM_REF2(il_simple_operation_c, il_simple_operator, il_operand) /* | function_name [il_operand_list] */ /* NOTE: The parameter 'called_function_declaration', 'extensible_param_count' and 'candidate_functions' are used to pass data between the stage 3 and stage 4. * data between the stage 3 and stage 4. * See the comment above function_invocation_c for more details */ SYM_REF2(il_function_call_c, function_name, il_operand_list, symbol_c *called_function_declaration; int extensible_param_count; std::vector candidate_functions;) /* | il_expr_operator '(' [il_operand] eol_list [simple_instr_list] ')' */ /* WARNING * The semantics of the il_expression_c.il_operand member is NOT what you may expect! * In order to simplify processing of the IL code, stage2 will prepend an artifical (and equivalent) 'LD ' IL instruction into the simple_instr_list * The il_expression_c.il_operand is maintained, in case we really need to handle it as a special case! * See the comments in iec_bison.yy for details and an example. */ SYM_REF3(il_expression_c, il_expr_operator, il_operand, simple_instr_list) /* il_jump_operator label */ SYM_REF2(il_jump_operation_c, il_jump_operator, label) /* il_call_operator prev_declared_fb_name * | il_call_operator prev_declared_fb_name '(' ')' * | il_call_operator prev_declared_fb_name '(' eol_list ')' * | il_call_operator prev_declared_fb_name '(' il_operand_list ')' * | il_call_operator prev_declared_fb_name '(' eol_list il_param_list ')' */ /* NOTE: The parameter 'called_fb_declaration'is used to pass data between stage 3 and stage4 (although currently it is not used in stage 4 */ SYM_REF4(il_fb_call_c, il_call_operator, fb_name, il_operand_list, il_param_list, symbol_c *called_fb_declaration;) /* | function_name '(' eol_list [il_param_list] ')' */ /* NOTE: The parameter 'called_function_declaration', 'extensible_param_count' and 'candidate_functions' are used to pass data between the stage 3 and stage 4. * See the comment above function_invocation_c for more details. */ SYM_REF2(il_formal_funct_call_c, function_name, il_param_list, symbol_c *called_function_declaration; int extensible_param_count; std::vector candidate_functions;) /* | il_operand_list ',' il_operand */ SYM_LIST(il_operand_list_c) /* | simple_instr_list il_simple_instruction */ SYM_LIST(simple_instr_list_c) /* il_simple_instruction: * il_simple_operation eol_list * | il_expression eol_list * | il_formal_funct_call eol_list */ /* NOTE: The parameters 'prev_il_instruction'/'next_il_instruction' are used to point to all previous/next il instructions that may be executed imedaitely before/after this instruction. * In case of an il instruction preceded by a label, the previous_il_instruction will include all IL instructions that jump to this label! * It is filled in by the flow_control_analysis_c during stage 3. * This will essentially be a doubly linked list of il_instruction_c and il_simple_instruction_c objects!! */ SYM_REF1(il_simple_instruction_c, il_simple_instruction, std::vector prev_il_instruction, next_il_instruction;) /* | il_initial_param_list il_param_instruction */ SYM_LIST(il_param_list_c) /* il_assign_operator il_operand * | il_assign_operator '(' eol_list simple_instr_list ')' */ SYM_REF3(il_param_assignment_c, il_assign_operator, il_operand, simple_instr_list) /* il_assign_out_operator variable */ SYM_REF2(il_param_out_assignment_c, il_assign_out_operator, variable) /*******************/ /* B 2.2 Operators */ /*******************/ /* NOTE: The parameter 'called_fb_declaration' is used to pass data between stage 3 and stage4 (although currently it is not used in stage 4 */ /* NOTE: The parameter 'deprecated_operation' indicates that the operation, with the specific data types being used, is currently defined * in the standard as being deprecated. This variable is filled in with the correct value in stage 3 (narrow_candidate_datatypes_c) * and currently only used in stage 3 (print_datatypes_error_c). */ SYM_REF0(LD_operator_c) SYM_REF0(LDN_operator_c) SYM_REF0(ST_operator_c) SYM_REF0(STN_operator_c) SYM_REF0(NOT_operator_c) SYM_REF0(S_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(R_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(S1_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(R1_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(CLK_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(CU_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(CD_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(PV_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(IN_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(PT_operator_c, symbol_c *called_fb_declaration;) SYM_REF0(AND_operator_c) SYM_REF0(OR_operator_c) SYM_REF0(XOR_operator_c) SYM_REF0(ANDN_operator_c) SYM_REF0(ORN_operator_c) SYM_REF0(XORN_operator_c) SYM_REF0(ADD_operator_c, bool deprecated_operation;) SYM_REF0(SUB_operator_c, bool deprecated_operation;) SYM_REF0(MUL_operator_c, bool deprecated_operation;) SYM_REF0(DIV_operator_c, bool deprecated_operation;) SYM_REF0(MOD_operator_c) SYM_REF0(GT_operator_c) SYM_REF0(GE_operator_c) SYM_REF0(EQ_operator_c) SYM_REF0(LT_operator_c) SYM_REF0(LE_operator_c) SYM_REF0(NE_operator_c) SYM_REF0(CAL_operator_c) SYM_REF0(CALC_operator_c) SYM_REF0(CALCN_operator_c) SYM_REF0(RET_operator_c) SYM_REF0(RETC_operator_c) SYM_REF0(RETCN_operator_c) SYM_REF0(JMP_operator_c) SYM_REF0(JMPC_operator_c) SYM_REF0(JMPCN_operator_c) /* any_identifier ASSIGN */ SYM_REF1(il_assign_operator_c, variable_name) /*| [NOT] any_identifier SENDTO */ SYM_REF2(il_assign_out_operator_c, option, variable_name) /***************************************/ /* B.3 - Language ST (Structured Text) */ /***************************************/ /***********************/ /* B 3.1 - Expressions */ /***********************/ SYM_REF1( ref_expression_c, exp) /* an extension to the IEC 61131-3 standard - based on the IEC 61131-3 v3 standard. REF() -> returns address of the varible! */ SYM_REF1(deref_expression_c, exp) /* an extension to the IEC 61131-3 standard - based on the IEC 61131-3 v3 standard. DREF() -> dereferences an address! */ SYM_REF1(deref_operator_c, exp) /* an extension to the IEC 61131-3 standard - based on the IEC 61131-3 v3 standard. ^ -> dereferences an address! */ SYM_REF2( or_expression_c, l_exp, r_exp) SYM_REF2(xor_expression_c, l_exp, r_exp) SYM_REF2(and_expression_c, l_exp, r_exp) SYM_REF2(equ_expression_c, l_exp, r_exp) SYM_REF2(notequ_expression_c, l_exp, r_exp) SYM_REF2( lt_expression_c, l_exp, r_exp) SYM_REF2( gt_expression_c, l_exp, r_exp) SYM_REF2( le_expression_c, l_exp, r_exp) SYM_REF2( ge_expression_c, l_exp, r_exp) SYM_REF2(add_expression_c, l_exp, r_exp, bool deprecated_operation;) SYM_REF2(sub_expression_c, l_exp, r_exp, bool deprecated_operation;) SYM_REF2(mul_expression_c, l_exp, r_exp, bool deprecated_operation;) SYM_REF2(div_expression_c, l_exp, r_exp, bool deprecated_operation;) SYM_REF2(mod_expression_c, l_exp, r_exp) SYM_REF2(power_expression_c, l_exp, r_exp) SYM_REF1(neg_expression_c, exp) SYM_REF1(not_expression_c, exp) /* formal_param_list -> may be NULL ! */ /* nonformal_param_list -> may be NULL ! */ /* NOTES: * The parameter 'called_function_declaration'... * ...is used to pass data between the stage 3 and stage 4. * The IEC 61131-3 standard allows for overloaded standard functions. This means that some * function calls are not completely defined by the name of the function being called, * and need to be disambiguated with using the data types of the parameters being passed. * Stage 3 does this to verify semantic correctness. * Stage 4 also needs to do this in order to determine which function to call. * It does not make sense to determine the exact function being called twice (once in stage 3, * and again in stage 4), so stage 3 will store this info in the parameter called_function_declaration * for stage 4 to use it later on. * The parameter 'candidate_functions'... * ...is used to pass data between two passes within stage 3 * (actually between fill_candidate_datatypes_c and narrow_candidate_datatypes_c). * It is used to store all the functions that may be legally called with the current parameters * being used in this function invocation. Note that the standard includes some standard functions * that have the exact same input parameter types, but return different data types. * In order to determine which of these functions should be called, we first create a list * of all possible functions, and then narrow down the list (hopefully down to 1 function) * once we know the data type that the function invocation must return (this will take into * account the expression in which the function invocation is inserted/occurs). * The 'called_function_declaration' will eventually be set (in stage 3) to one of * the functions in the 'candidate_functions' list! * The parameter 'extensible_param_count'... * ...is used to pass data between the stage 3 and stage 4. * The IEC 61131-3 standard allows for extensible standard functions. This means that some * standard functions may be called with a variable number of paramters. Stage 3 will store * in extensible_param_count the number of parameters being passed to the extensible parameter. */ SYM_REF3(function_invocation_c, function_name, formal_param_list, nonformal_param_list, symbol_c *called_function_declaration; int extensible_param_count; std::vector candidate_functions;) /********************/ /* B 3.2 Statements */ /********************/ SYM_LIST(statement_list_c) /*********************************/ /* B 3.2.1 Assignment Statements */ /*********************************/ SYM_REF2(assignment_statement_c, l_exp, r_exp) /*****************************************/ /* B 3.2.2 Subprogram Control Statements */ /*****************************************/ /* RETURN */ SYM_REF0(return_statement_c) /* fb_name '(' [param_assignment_list] ')' */ /* formal_param_list -> may be NULL ! */ /* nonformal_param_list -> may be NULL ! */ /* NOTE: The parameter 'called_fb_declaration'is used to pass data between stage 3 and stage4 (although currently it is not used in stage 4 */ SYM_REF3(fb_invocation_c, fb_name, formal_param_list, nonformal_param_list, symbol_c *called_fb_declaration;) /* helper symbol for fb_invocation */ /* param_assignment_list ',' param_assignment */ SYM_LIST(param_assignment_list_c) /* variable_name ASSIGN expression */ SYM_REF2(input_variable_param_assignment_c, variable_name, expression) /* [NOT] variable_name '=>' variable */ SYM_REF3(output_variable_param_assignment_c, not_param, variable_name, variable) /* helper CLASS for output_variable_param_assignment */ SYM_REF0(not_paramassign_c) /********************************/ /* B 3.2.3 Selection Statements */ /********************************/ /* IF expression THEN statement_list elseif_statement_list ELSE statement_list END_IF */ SYM_REF4(if_statement_c, expression, statement_list, elseif_statement_list, else_statement_list) /* helper symbol for if_statement */ SYM_LIST(elseif_statement_list_c) /* helper symbol for elseif_statement_list */ /* ELSIF expression THEN statement_list */ SYM_REF2(elseif_statement_c, expression, statement_list) /* CASE expression OF case_element_list ELSE statement_list END_CASE */ SYM_REF3(case_statement_c, expression, case_element_list, statement_list) /* helper symbol for case_statement */ SYM_LIST(case_element_list_c) /* case_list ':' statement_list */ SYM_REF2(case_element_c, case_list, statement_list) SYM_LIST(case_list_c) /********************************/ /* B 3.2.4 Iteration Statements */ /********************************/ /* FOR control_variable ASSIGN expression TO expression [BY expression] DO statement_list END_FOR */ SYM_REF5(for_statement_c, control_variable, beg_expression, end_expression, by_expression, statement_list) /* WHILE expression DO statement_list END_WHILE */ SYM_REF2(while_statement_c, expression, statement_list) /* REPEAT statement_list UNTIL expression END_REPEAT */ SYM_REF2(repeat_statement_c, statement_list, expression) /* EXIT */ SYM_REF0(exit_statement_c)