/* description: Parses end executes JediScript expressions. */

/* lexical grammar */
%lex
%x DoubleQuotedString
%x SingleQuotedString
%x QuotedStringEscape
%%


\/\/([^\n\r]*)              /* skip single-line comments */
\/\*([\u0000-\uffff]*?)\*\/ /* skip multi-line comments */
\s+                         /* skip whitespace */

"function"                                    return 'function'
"return"                                      return 'return'
"if"                                          return 'if'
"else"                                        return 'else'
"while"                                       return 'while'
"for"                                         return 'for'
"break"                                       return 'break'
"continue"                                    return 'continue'
"let"                                         return 'let'
"const"                                       return 'const'
"==="                                         return '==='
"=>"                                          return '=>'
"="                                           return '='
"{"                                           return '{'
"}"                                           return '}'
";"                                           return ';'
","                                           return ','
"true"                                        return 'true'
"false"                                       return 'false'
"NaN"                                         return 'NaN'
"Infinity"                                    return 'Infinity'
"null"                                        return 'emptylist'
"["                                           return '['
"]"                                           return ']'

'""'                                          return 'EmptyString'
"''"                                          return 'EmptyString'
'"'                                           this.begin('DoubleQuotedString');
"'"                                           this.begin('SingleQuotedString');
<DoubleQuotedString,SingleQuotedString>\\     this.begin('QuotedStringEscape');
<DoubleQuotedString>'"'                       this.popState();
<SingleQuotedString>"'"                       this.popState();
<QuotedStringEscape>(.|\r\n|\n)               { this.popState(); return 'QuotedStringEscape'; } /* The newlines are there because we can span strings across lines using \ */
<DoubleQuotedString>[^"\\]*                   return 'QuotedString';
<SingleQuotedString>[^'\\]*                   return 'QuotedString';


[A-Za-z_][A-Za-z0-9_]*                        return 'Identifier' /* TODO: non-ASCII identifiers */

[0-9]+("."[0-9]+)?([eE][\-+]?[0-9]+)?\b       return 'FLOAT_NUMBER' /* 3.1, 3.1e-7 */
[0-9]+\b                                      return 'INT_NUMBER'

"+"                                           return '+'
"-"                                           return '-'
"*"                                           return '*'
"/"                                           return '/'
"%"                                           return '%'
"!=="                                         return '!=='
"<="                                          return '<='
">="                                          return '>='
"<"                                           return '<'
">"                                           return '>'
"!"                                           return '!'
"&&"                                          return '&&'
"||"                                          return '||'
"("                                           return '('
")"                                           return ')'
"?"                                           return '?'
":"                                           return ':'

<<EOF>>                                       return 'EOF'
.                                             return 'INVALID'

/lex

/* operator associations and precedence */

%left  ';'
%right '='
%left  '=>' ARROW
%right '?' ':'
%left  '||'
%left  '&&'
%left  '===' '!=='
%left  '<' '>' '<=' '>='
%left  '+' '-'
%left  '*' '/' '%'
%right '!' UMINUS UPLUS
%left  '[' ']'
%left  '.'

%% /* language grammar */

program
  : statements EOF
    { return $1; }
  ;

statements
  :
    { $$ = ""; }
  | statement statements
    { $$ = $1 + $2; }
  ;

statement
  :
  ifstatement

  | whilestatement

  | forstatement

  | 'function ' identifier '(' identifiers ')' '{' statements '}'
    {{
      $$ = "function" + $2 + "(" + $4 + ") {" + $7 + "}" ;
    }}
  | constdeclaration
  | letdeclaration
  | '{' statements '}'
        {{
      $$ = "{" + $2 + "}";
        }}

  | assignment ';'
      {{
      $$ = $1 + ";";
        }}

  | expression ';'
    {{
      $$ = $1 + ";";
        }}
  | 'return' expression ';'
    {{
      $$ = "return " + $2 + ";";
        }}


  | break ';'
    {{
      $$ = "break;";
    }}
  | continue ';'
    {{
      $$ = "continue;";
    }}

  ;

letdeclaration
  :
  'let' identifier '=' expression ';'
    {{
      $$ = "var " + $2 + "=" + $4 + ";";
    }}
  ;

constdeclaration
  :
  'const' identifier '=' expression ';'
    {{
      $$ = "var " + $2 + "=" + $4 + ";";
    }}
  ;


assignment
  :
  expression '=' expression
    {{
      $$ = $1 + "=" + $3;
    }}
  ;

ifstatement
  :
  'if' '(' expression ')' '{' statements '}' 'else' '{' statements '}'
    {{
      $$ = "if (" + $3 + ") {" + $6 + "} else {" + $10 + "}";
    }}
  | 'if' '(' expression ')' '{' statements '}' 'else' ifstatement
    {{
      $$ = "if (" + $3 + ") {" + $6 + "} else " + $9;
    }}
  ;


whilestatement
  :
  'while' '(' expression ')' '{' statements '}'
    {{
      $$ = "while (" + $3 + ") {" + $6 + "}";
    }}
  ;

forstatement
  :
    'for' '(' forinitialiser expression ';' forfinaliser ')' '{' statements '}'
    {{
      $$ = "for (" + $3 + $4 + ";" + $6 + ") {" + $9 + "}";
    }}
  ;

forinitialiser
  :
  letdeclaration
  | assignment ';'
  {{
      $$ = $1 + ";";
    }}
  ;

forfinaliser
  :
  assignment
  ;


expression
  :
  expression '+' expression
    {{
      $$ = $1 + "+" + $3;
    }}
  | expression '-' expression
    {{
      $$ = $1 + "-" + $3;
    }}
  | expression '*' expression
    {{
      $$ = $1 + "*" + $3;
    }}
  | expression '/' expression
    {{
      $$ = $1 + "/" + $3;
    }}
  | expression '%' expression
    {{
      $$ = $1 + "%" + $3;
    }}
  | '-' expression %prec UMINUS
    {{
      $$ = "-" + $1;
    }}
  | '+' expression %prec UPLUS
    {{
      $$ = "+" + $1;
    }}
  | '!' expression
    {{
      $$ = "!" + $1;
    }}
  | expression '&&' expression
    {{
      $$ = $1 + "&&" + $3;
    }}
  | expression '||' expression
    {{
      $$ = $1 + "||" + $3;
    }}
  | expression '===' expression
    {{
      $$ = $1 + "===" + $3;
    }}
  | expression '!==' expression
    {{
      $$ = $1 + "!==" + $3;
    }}
  | expression '>' expression
    {{
      $$ = $1 + ">" + $3;
    }}
  | expression '<' expression
    {{
      $$ = $1 + "<" + $3;
    }}
  | expression '>=' expression
    {{
      $$ = $1 + ">=" + $3;
    }}
  | expression '<=' expression
    {{
      $$ = $1 + "<=" + $3;
    }}
  | '(' identifiers ')' '=>' expression    %prec ARROW
    {{
      $$ = "(function(" + $2 + "){ return " + $5 + ";})";
    }}
  | '(' identifiers ')' '=>' '{' statements '}'    %prec ARROW
    {{
      $$ = "(function(" + $2 + "){ " + $6 + "})";
    }}
  | identifier '=>' expression
    {{
      $$ = "(function(" + $1 + "){ return " + $3 + ";})";
    }}
  | identifier '=>' '{' statements '}'
	{{
	$$ = "(function(" + $1 + "){ " + $4 + "})";
	}}

  | expression '[' expression ']'
    {{
      $$ = $1 + "[" + $3 + "]"
    }}

  | '(' expression ')'
    {$$ = "(" + $2 + ")";}

  | constants
    { $$ = $1; }

  | identifier
    { $$ = $1; }

  | '(' expression ')' '(' expressions ')'
    {{
      $$ = "(" + $2 + ")(" + $5 + ")";
    }}

  | '[' expressions ']'
    {{
      $$ = "[" + $2 + "]";
    }}

  | identifier '(' expressions ')'
    {{
      $$ = $1 + "(" + $3 + ")";
    }}

  | expression '?' expression ':' expression
    {{
      $$ = $1 + "?" + $3 + ":" + $5;
    }}
  ;

constants
  :
  'FLOAT_NUMBER'
    { $$ = String(parseFloat(yytext)); }

  | 'INT_NUMBER'
    { $$ = String(parseInt(yytext, 10)); }

  | 'true'
    { $$ = 'true'; }

  | 'false'
    { $$ = 'false'; }

  | 'NaN'
    { $$ = 'NaN'; }

  | 'Infinity'
    { $$ = 'Infinity'; }

  | quotedstring

  | 'emptylist'
    { $$ = 'null'; }
  ;

quotedstring
  :
    'EmptyString'
  {
    $$ = '""';
  }
  | 'QuotedString'
  | 'QuotedStringEscape'
  {
    switch (yytext)
    {
      case 'b':   $$ = '\b'; break;
      case 'n':   $$ = '\n'; break;
      case 'r':   $$ = '\r'; break;
      case 't':   $$ = '\t'; break;
      case "'":   $$ = "'"; break;
      case '"':   $$ = '"'; break;
      case '\\':    $$ = '\\'; break;
      case '\n':
      case '\r\n':  $$ = ''; break;
      default:    $$ = '\\' + $1; break;
    }
  }
  | 'QuotedStringEscape' quotedstring
  {
    switch ($1)
    {
      case 'b':   $$ = '\b'; break;
      case 'n':   $$ = '\n'; break;
      case 'r':   $$ = '\r'; break;
      case 't':   $$ = '\t'; break;
      case "'":   $$ = "'"; break;
      case '"':   $$ = '"'; break;
      case '\\':    $$ = '\\'; break;
      case '\n':
      case '\r\n':  $$ = ''; break;
      default:    $$ = '\\' + $1; break;
    }
    $$ += $2;
  }
  | 'QuotedString' quotedstring
  {
    $$ = $1 + $2;
  }
  ;

expressions
  :
  nonemptyexpressions
    { $$ = $1; }
  | /* NOTHING */
    { $$ = ""; }
  ;

nonemptyexpressions
  :
  expression ',' nonemptyexpressions
    { $$ = $1 + "," + $3; }
  | expression
    { $$ = $1; }
  ;

identifiers
  :
  nonemptyidentifiers
    { $$ = $1; }
  | /* NOTHING */
    { $$ = ""; }
  ;

nonemptyidentifiers
  :
  identifier ',' nonemptyidentifiers
    { $$ = $1 + "," + $3; }
  | identifier
    { $$ = $1; }
  ;

identifier
  :
  'Identifier'
    {{
      $$ = yytext;
    }}
  ;