329 lines
8.0 KiB
Plaintext
329 lines
8.0 KiB
Plaintext
# PLATYPUS Language Specification
|
|
|
|
### 2.1 Input Elements and Tokens
|
|
|
|
<input character> ->
|
|
ASCII characters but not SEOF
|
|
|
|
<input> ->
|
|
<input elements> SEOF
|
|
|
|
<input elements> ->
|
|
<input element> | <input elements> <input element>
|
|
|
|
<token> ->
|
|
<variable identifier> | <keyword> | <floating-point literal>
|
|
| <integer literal> | <string literal> | <separator> | <operator>
|
|
|
|
### 2.2 White Space
|
|
|
|
<white space> ->
|
|
ASCII SP character (space)
|
|
| ASCII HT character (horizontal tab)
|
|
| ASCII VT character (vertical tab)
|
|
| ASCII FF character (form feed)
|
|
| <line terminator>
|
|
|
|
<line terminator> ->
|
|
CR | LF | CR LF
|
|
|
|
### 2.3 Comments
|
|
|
|
<comment> ->
|
|
!< <opt_characters in line> <line terminator>
|
|
|
|
<characters in line> ->
|
|
<comment character> | <characters in line> <comment character>
|
|
|
|
<comment character> ->
|
|
<input character> but not <line terminator>
|
|
|
|
### 2.4 Variable Identifiers
|
|
|
|
<variable identifier> ->
|
|
<arithmetic variable identifier> | <string variable identifier>
|
|
|
|
<arithmetic identifier> ->
|
|
<letter> <opt_letters or digits>
|
|
|
|
<opt_letters or digits> ->
|
|
ε | <letters or digits>
|
|
|
|
<letters or digits> ->
|
|
<letter or digit> | <letters or digits> <letter or digit>
|
|
|
|
<letter> ->
|
|
[a-z] | [A-Z]
|
|
|
|
<letter or digit> ->
|
|
<letter> | <digit>
|
|
|
|
<string variable identifier> ->
|
|
<arithmetic variable identifier>#
|
|
|
|
### 2.5 Keywords
|
|
|
|
<keyword> ->
|
|
PLATYPUS | IF | THEN | ELSE | USING | REPEAT | INPUT | OUTPUT
|
|
|
|
### 2.6 Integer Literals
|
|
|
|
<integer literal> ->
|
|
<decimal integer literal> | <octal integer literal>
|
|
|
|
<decimal integer literal> ->
|
|
0 | <non-zero digit> <opt_digits>
|
|
|
|
<opt_digits> ->
|
|
ε | <digits>
|
|
|
|
<digits> ->
|
|
<digit> | <digits> <digit>
|
|
|
|
<digit> ->
|
|
0 | <non-zero digit>
|
|
|
|
<non-zero digit> -> one of
|
|
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
|
|
|
|
<octal integer literal> ->
|
|
0 <octal digit> <octal digits>
|
|
|
|
<octal digit> ->
|
|
0 | 1 | 2 | 3 | 4 | 5 | 6 | 7
|
|
|
|
<octal digits> ->
|
|
<octal digit> | <octal digits> <octal digit>
|
|
|
|
|
|
### 2.7 Floating-point Literals
|
|
|
|
<floating-point literal> ->
|
|
<decimal integer literal> . <opt_digits>
|
|
|
|
### 2.8 String Literals
|
|
|
|
<opt_string literal> ->
|
|
ε | <string literal>
|
|
|
|
<string literal> ->
|
|
"<opt_string characters>"
|
|
|
|
<opt_string characters> ->
|
|
ε | <string characters>
|
|
|
|
<string characters> ->
|
|
<input character> | <string characters> <input character>
|
|
|
|
### 2.9 Separators
|
|
|
|
<separator> ->
|
|
( | ) | { | } | , | ; | " |.
|
|
|
|
### 2.10 Operators
|
|
|
|
<operator> ->
|
|
<arithmetic operator> | <string concatenation operator>
|
|
| <relational operator> | <logical operator>
|
|
| <assignment operator>
|
|
|
|
<arithmetic operator> ->
|
|
+ | - | * | /
|
|
|
|
<string concatenation operator> ->
|
|
<<
|
|
|
|
<relational operator> ->
|
|
> | < | == | <>
|
|
|
|
<logical operator> ->
|
|
.AND. | .OR.
|
|
|
|
<assignment operator> ->
|
|
=
|
|
|
|
## 3. The PLATYPUS Syntactic Specification
|
|
### 3.1 PLATYPUS Program
|
|
|
|
<program> ->
|
|
PLATYPUS {<opt_statements>} SEOF
|
|
|
|
<opt_statements> ->
|
|
ε | <statements>
|
|
|
|
<statements> ->
|
|
<statement> | <statements> <statement>
|
|
|
|
### 3.2 Statements
|
|
|
|
<statement> ->
|
|
<assignment statement>
|
|
| <selection statement>
|
|
| <iteration statement>
|
|
| <input statement>
|
|
| <output statement>
|
|
|
|
### 3.3 Assignment Statement
|
|
|
|
<assignment statement> ->
|
|
<assignment expression> ;
|
|
|
|
<assignment expression> ->
|
|
<arithmetic variable identifier> = <arithmetic expression>
|
|
| <string variable identifier> = <string expression>
|
|
|
|
#### 3.2.2 Selection Statement (`if` statement)
|
|
|
|
<selection statement> ->
|
|
IF (<conditional expression>) THEN <opt_statements>
|
|
ELSE {<opt_statements>};
|
|
|
|
#### 3.2.3 Iteration Statement (the loop statement)
|
|
|
|
<iteration statement> ->
|
|
USING (<assignment expression> , <conditional expression>, <assignment expression>) REPEAT { <opt_statements> };
|
|
|
|
#### 3.2.4 Input Statement
|
|
|
|
<input statement> ->
|
|
INPUT (<variable list>);
|
|
|
|
<opt_variable list> ->
|
|
ε | <variable list>
|
|
|
|
/** New Variable List version below
|
|
<variable list> ->
|
|
<variable identifier> | <variable list>,<variable identifier>
|
|
**/
|
|
|
|
<variable list> ->
|
|
<variable identifier> <variable list'>
|
|
|
|
<variable list'> ->
|
|
, <variable identifier> <variable list'> | E
|
|
|
|
#### 3.2.5 Output Statement
|
|
|
|
<output statement> ->
|
|
OUTPUT(<opt_variable list> | <opt_string literal>);
|
|
|
|
### 3.3 Expressions
|
|
#### 3.3.1 Arithmetic Expressions
|
|
|
|
<arithmetic expression> ->
|
|
<unary arithmetic expression>
|
|
| <additive arithmetic expression>
|
|
|
|
<unary arithmetic expression> ->
|
|
- <primary arithmetic expression>
|
|
| + <primary arithmetic expression>
|
|
|
|
/** New Version of Additive Arithmetic Expressions below
|
|
<additive arithmetic expression> ->
|
|
<additive arithmetic expression> + <multiplicative arithmetic expression>
|
|
| <additive arithmetic expression> - <multiplicative arithmetic expression>
|
|
| <multiplicative arithmetic expression>
|
|
**/
|
|
|
|
<additive arihtmetic expression> ->
|
|
<multiplicative arithmetic expression> <additive arithmetic expression'>
|
|
|
|
<additive arithmetic expression'> ->
|
|
+ <multiplicative arithmetic expression> <additive arithmetic expression'>
|
|
| - <multiplicative arithmetic expression> <additive arithmetic expression'>
|
|
|
|
/** New Version of Mult. Arithmetic Expressions below
|
|
<multiplicative arithmetic expression> ->
|
|
<multiplicative arithmetic expression> * <primary arithmetic expression>
|
|
| <multiplicative arithmetic expression> / <primary arithmetic expression>
|
|
| <primary arithmetic expression>
|
|
**/
|
|
<multiplicative arithmetic expression> ->
|
|
<primary arithmetic expression> <multiplicative arithmetic expression'>
|
|
|
|
<multiplicative arithmetic expression'> ->
|
|
* <primary arithmetic expression> <multiplicative arithmetic expression'>
|
|
| / <primary arithmetic expression> <multiplicative arithmetic expression'>
|
|
|
|
<primary arithmetic expression> ->
|
|
<variable identifier>
|
|
| <floating-point literal>
|
|
| <integer literal>
|
|
| (<arithmetic expression>)
|
|
|
|
#### 3.3.2 String Expression
|
|
/** New version of String Expressions below
|
|
<string expression> ->
|
|
<primary string expression>
|
|
| <string expression> << <primary string expression>
|
|
**/
|
|
<string expression> ->
|
|
<primary string expression> <string expression'>
|
|
|
|
<string expression'> ->
|
|
<< <primary string expression> <string expression'> | E
|
|
|
|
<primary string expression> ->
|
|
<string variable identifier>
|
|
| <string literal>
|
|
|
|
#### 3.3.3 Conditional Expression
|
|
|
|
<conditional expression> ->
|
|
<logical OR expression>
|
|
|
|
/** New Logical OR and Logical AND expressions below
|
|
<logical OR expression> ->
|
|
<logical AND expression>
|
|
| <logical OR expression> .OR. <logical AND expression>
|
|
|
|
<logical AND expression> ->
|
|
<relational expression>
|
|
| <logical AND expression> .AND. <relational expression>
|
|
**/
|
|
<logical OR expression> ->
|
|
<logical AND expression> <logical OR expression'>
|
|
|
|
<logical OR expression'> ->
|
|
.OR. <logical AND expression> <logical OR expression'>
|
|
|
|
<logical AND expression> ->
|
|
<relational expression> <logical AND expression'>
|
|
|
|
<logical AND expression'> ->
|
|
.AND. <relational expression> <logical AND expression'>
|
|
|
|
|
|
#### 3.3.4 Relational Expressions
|
|
|
|
/** New version of Relational expressions below
|
|
<relational expression> ->
|
|
<primary a_relational expression> <relational operator> <primary a_relational expression>
|
|
| <primary s_relational expression> <relational operator> <primary s_relational expression>
|
|
**/
|
|
|
|
<relational expression> ->
|
|
<primary a_relational expression> <primary a_relational expression'>
|
|
| <primary s_relational expression> <primary s_relational expression'>
|
|
|
|
|
|
<primary a_relational expression> ->
|
|
<floating-point literal>
|
|
| <integer literal>
|
|
| <variable identifier>
|
|
|
|
<primary a_relational expression'> ->
|
|
== <primary a_relational expression>
|
|
| <> <primary a_relational expression>
|
|
| > <primary a_relational expression>
|
|
| < <primary a_relational expression>
|
|
|
|
<primary s_relational expression> ->
|
|
<string literal> | <string variable identifier>
|
|
|
|
<primary s_relational expression'> ->
|
|
== <primary s_relational expression>
|
|
| <> <primary s_relational expression>
|
|
| > <primary s_relational expression>
|
|
| < <primary s_relational expression>
|