Rudimentary language specification
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# PLATYPUS Language Specification
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## Lexical Specification (INCOMPLETE)
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## 2. Lexical Specification (INCOMPLETE)
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## NOTE: **This is incredibly incomplete and broken, I am simply writing this down and will fix it as I read along the informal language specification provided to me**
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1. Input Elements and Tokens
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### 2.1 Input Elements and Tokens
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```
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<input character> ->
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ASCII characters but not SEOF
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@ -19,7 +19,7 @@
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<variable identifier> | <keyword> | <floating-point literal>
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| <integer literal> | <string literal> | <separator> | <operator>
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```
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2. White Space
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### 2.2 White Space
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```
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<white space> ->
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ASCII SP character (space)
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@ -31,7 +31,7 @@
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<line terminator> ->
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CR | LF | CR LF
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```
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3. Comments
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### 2.3 Comments
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```
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<comment> ->
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!< <opt_characters in line> <line terminator>
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<comment character> ->
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<input character> but not <line terminator>
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```
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4. Variable Identifiers
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### 2.4 Variable Identifiers
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```
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<variable identifier> ->
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<arithmetic variable identifier> | <string variable identifier>
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<string variable identifier> ->
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<arithmetic variable identifier>#
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```
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5. Keywords
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### 2.5 Keywords
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```
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<keyword> ->
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PLATYPUS | IF | THEN | ELSE | USING | REPEAT | INPUT | OUTPUT
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```
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6. Integer Literals
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### 2.6 Integer Literals
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```
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<integer literal> ->
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<decimal integer literal> | <octal integer literal>
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@ -93,3 +93,160 @@
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<octal digits> ->
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<octal digit> | <octal digits> <octal digit>
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```
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### 2.7 Floating-point Literals
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```
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<floating-point literal> ->
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<decimal integer literal> . <opt_digits>
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```
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### 2.8 String Literals
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```
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<string literal> ->
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"<opt_string characters>"
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<string chacters> ->
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<input character> | <string characters> <input character>
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```
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### 2.9 Separators
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```
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<separator> -> one of
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( ) { } , ; " .
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```
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### 2.10 Operators
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```
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<operator> ->
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<arithmetic operator> | <string concatenation operator>
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| <relational operator> | <logical operator>
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| <assignment operator>
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<arithmetic operator> -> one of
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+ - * /
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<string concatenation operator> -> one of
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> < == <>
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<logical operator> ->
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.AND. | .OR.
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<assignment operator> ->
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=
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```
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## 3. The PLATYPUS Syntatic Specification
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### 3.1 PLATYPUS Program
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```
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<program> ->
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PLATYPUS {<opt_statements>} SEOF
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<statements> ->
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<statement> | <statements> <statement>
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```
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### 3.2 Statements
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```
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<statement> ->
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<assignment statement>
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| <selection statement>
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| <iteration statement>
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| <input statement>
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| <output statement>
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```
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### 3.3 Assignment Statement
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```
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<assignment statement> ->
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<assignment expression>
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<assignment expression> ->
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AVID = <arithmetic expression>
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| SVID = <string expression>
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```
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#### 3.2.2 Selection Statement (`if` statement)
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```
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<selection statement> ->
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IF (<conditional expression>) THEN <statements>
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ELSE {<opt_statements>};
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```
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#### 3.2.3 Iteration Statement (the loop statement)
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```
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<iteration statement> ->
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<TBC>
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```
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#### 3.2.4 Input Statement
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```
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<input statement> ->
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INPUT (<variable list>);
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<variable list> ->
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<variable identifier> | <variable list>,<variable identifier>
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```
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#### 3.2.5 Output Statement
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```
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<output statement> ->
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<TBC>
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```
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### 3.3 Expressions
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#### 3.3.1 Arithmetic Expressions
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```
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<arithmetic expression> ->
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<unary arithmetic expression>
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| <additive arithmetic expression>
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<unary arithmetic expression> ->
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- <primary arithmetic expression>
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| + <primary arithmetic expression
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<additive arithmetic expression> ->
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<additive arithmetic expression> + <multiplicative arithmetic expression>
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| <additive arithmetic expression> - <multiplicative arithmetic expression>
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| <multiplicative arithmetic expression>
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<multiplicative arithmetic expression> ->
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<multiplicative arithmetic expression> * <primary arithmetic expression>
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| <multiplicative arithmetic expression> / <primary arithmetic expression>
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| <primary arithmetic expression>
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<primary arithmetic expression> ->
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<variable identifier>
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| <floating-point literal>
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| <integer literal>
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| (<arithmetic expression>)
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```
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#### 3.3.2 String Expression
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```
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<string expression> ->
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<primary string expression>
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| <string expression> << <primary string expression>
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<primary string expression> ->
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<string variable identifier>
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| <string literal>
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```
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#### 3.3.3 Conditional Expression
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```
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<conditional expression> ->
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<logical OR expression>
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<logical OR expression> ->
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<TBC>
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<logical AND expression> ->
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<TBC>
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```
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#### 3.3.4 Relational Expression
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```
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<relational expression> ->
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<primary a_relational expression> == <primary a_relational expression>
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| <primary a_relational expression> <= <primary a_relational expression>
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| <primary a_relational expression> > <primary a_relational expression>
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| <primary a_relational expression> < <primary a_relational expression>
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| <primary s_relational expression> == <primary s_relational expression>
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| <primary s_relational expression> <= <primary s_relational expression>
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| <primary s_relational expression> > <primary s_relational expression>
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| <primary s_relational expression> < <primary s_relational expression>
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<primary a_relational expression> ->
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<floating-point literal>
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| <integer literal>
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| <variable identifier>
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<primary s_relational expression> ->
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<TBC>
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```
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