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r200fcb3 r9e6d652 11 11 %% Created On : Wed Apr 6 14:53:29 2016 12 12 %% Last Modified By : Peter A. Buhr 13 %% Last Modified On : Tue Dec 11 23:19:26 201814 %% Update Count : 34 0013 %% Last Modified On : Sun May 5 18:24:50 2019 14 %% Update Count : 3489 15 15 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 16 16 … … 193 193 \end{center} 194 194 While the \CFA I/O looks similar to the \Index*[C++]{\CC{}} output style, there are important differences, such as automatic spacing between variables as in \Index*{Python} (see~\VRef{s:IOLibrary}). 195 195 196 196 197 \subsection{Background} … … 432 433 which conditionally includes the correct header file, if the program is compiled using \Indexc{gcc} or \Indexc{cfa}. 433 434 435 The \CFA translator has multiple steps. 436 The following flags control how the tranlator works, the stages run, and printing within a stage. 437 The majority of these flags are used by \CFA developers, but some are occasionally useful to programmers. 438 \begin{description}[topsep=5pt,itemsep=0pt,parsep=0pt] 439 \item 440 \Indexc{-h}\index{translator option!-h@{©-h©}}, \Indexc{--help}\index{translator option!--help@{©--help©}} \, print help message 441 \item 442 \Indexc{-l}\index{translator option!-l@{©-l©}}, \Indexc{--libcfa}\index{translator option!--libcfa@{©--libcfa©}} \, generate libcfa.c 443 \item 444 \Indexc{-L}\index{translator option!-L@{©-L©}}, \Indexc{--linemarks}\index{translator option!--linemarks@{©--linemarks©}} \, generate line marks 445 \item 446 \Indexc{-m}\index{translator option!-m@{©-m©}}, \Indexc{--no-main}\index{translator option!--no-main@{©--no-main©}} \, do not replace main 447 \item 448 \Indexc{-N}\index{translator option!-N@{©-N©}}, \Indexc{--no-linemarks}\index{translator option!--no-linemarks@{©--no-linemarks©}} \, do not generate line marks 449 \item 450 \Indexc{-n}\index{translator option!-n@{©-n©}}, \Indexc{--no-prelude}\index{translator option!--no-prelude@{©--no-prelude©}} \, do not read prelude 451 \item 452 \Indexc{-p}\index{translator option!-p@{©-p©}}, \Indexc{--prototypes}\index{translator option!--prototypes@{©--prototypes©}} \, generate prototypes for prelude functions 453 \item 454 \Indexc{-P}\index{translator option!-P@{©-P©}}, \Indexc{--print}\index{translator option!--print@{©--print©}} \, one of: 455 \begin{description}[topsep=0pt,itemsep=0pt,parsep=0pt] 456 \item 457 \Indexc{altexpr}\index{translator option!-P@{©-P©}!©altexpr©}\index{translator option!--print@{©-print©}!©altexpr©} \, alternatives for expressions 458 \item 459 \Indexc{ascodegen}\index{translator option!-P@{©-P©}!©ascodegen©}\index{translator option!--print@{©-print©}!©ascodegen©} \, as codegen rather than AST 460 \item 461 \Indexc{ast}\index{translator option!-P@{©-P©}!©ast©}\index{translator option!--print@{©-print©}!©ast©} \, AST after parsing 462 \item 463 \Indexc{astdecl}\index{translator option!-P@{©-P©}!©astdecl©}\index{translator option!--print@{©-print©}!©astdecl©} \, AST after declaration validation pass 464 \item 465 \Indexc{asterr}\index{translator option!-P@{©-P©}!©asterr©}\index{translator option!--print@{©-print©}!©asterr©} \, AST on error 466 \item 467 \Indexc{astexpr}\index{translator option!-P@{©-P©}!©astexpr©}\index{translator option!--print@{©-print©}!©altexpr©} \, AST after expression analysis 468 \item 469 \Indexc{astgen}\index{translator option!-P@{©-P©}!©astgen©}\index{translator option!--print@{©-print©}!©astgen©} \, AST after instantiate generics 470 \item 471 \Indexc{box}\index{translator option!-P@{©-P©}!©box©}\index{translator option!--print@{©-print©}!©box©} \, before box step 472 \item 473 \Indexc{ctordtor}\index{translator option!-P@{©-P©}!©ctordtor©}\index{translator option!--print@{©-print©}!©ctordtor©} \, after ctor/dtor are replaced 474 \item 475 \Indexc{codegen}\index{translator option!-P@{©-P©}!©codegen©}\index{translator option!--print@{©-print©}!©codegen©} \, before code generation 476 \item 477 \Indexc{declstats}\index{translator option!-P@{©-P©}!©declstats©}\index{translator option!--print@{©-print©}!©declstats©} \, code property statistics 478 \item 479 \Indexc{parse}\index{translator option!-P@{©-P©}!©parse©}\index{translator option!--print@{©-print©}!©parse©} \, yacc (parsing) debug information 480 \item 481 \Indexc{pretty}\index{translator option!-P@{©-P©}!©pretty©}\index{translator option!--print@{©-print©}!©pretty©} \, prettyprint for ascodegen flag 482 \item 483 \Indexc{resolver}\index{translator option!-P@{©-P©}!©resolver©}\index{translator option!--print@{©-print©}!©resolver©} \, before resolver step 484 \item 485 \Indexc{rproto}\index{translator option!-P@{©-P©}!©rproto©}\index{translator option!--print@{©-print©}!©rproto©} \, resolver-proto instance 486 \item 487 \Indexc{rsteps}\index{translator option!-P@{©-P©}!©rsteps©}\index{translator option!--print@{©-print©}!©rsteps©} \, resolver steps 488 \item 489 \Indexc{symevt}\index{translator option!-P@{©-P©}!©symevt©}\index{translator option!--print@{©-print©}!©symevt©} \, symbol table events 490 \item 491 \Indexc{tree}\index{translator option!-P@{©-P©}!©tree©}\index{translator option!--print@{©-print©}!©tree©} \, parse tree 492 \item 493 \Indexc{tuple}\index{translator option!-P@{©-P©}!©tuple©}\index{translator option!--print@{©-print©}!©tuple©} \, after tuple expansion 494 \end{description} 495 \item 496 \Indexc{--prelude-dir} <directory> \, prelude directory for debug/nodebug 497 \item 498 \Indexc{-S}\index{translator option!-S@{©-S©}!©counters,heap,time,all,none©}, \Indexc{--statistics}\index{translator option!--statistics@{©--statistics©}!©counters,heap,time,all,none©} <option-list> \, enable profiling information: 499 \begin{description}[topsep=0pt,itemsep=0pt,parsep=0pt] 500 \item 501 \Indexc{counters,heap,time,all,none} 502 \end{description} 503 \item 504 \Indexc{-t}\index{translator option!-t@{©-t©}}, \Indexc{--tree}\index{translator option!--tree@{©--tree©}} build in tree 505 \end{description} 506 434 507 435 508 \section{Backquote Identifiers} … … 508 581 509 582 As for \Index{division}, there are exponentiation operators for integral and floating types, including the builtin \Index{complex} types. 510 Unsigned integral exponentiation\index{exponentiation!unsigned integral} is performed with repeated multiplication\footnote{The multiplication computation is $O(\log y)$.} (or shifting if the base is 2). 511 Signed integral exponentiation\index{exponentiation!signed integral} is performed with repeated multiplication (or shifting if the base is 2), but yields a floating result because $x^{-y}=1/x^y$. 512 Hence, it is important to designate exponent integral-constants as unsigned or signed: ©3 \ 3u© return an integral result, while ©3 \ 3© returns a floating result. 513 Floating exponentiation\index{exponentiation!floating} is performed using \Index{logarithm}s\index{exponentiation!logarithm}, so the base cannot be negative. 514 \begin{cfa} 515 sout | 2 ®\® 8u | 4 ®\® 3u | -4 ®\® 3u | 4 ®\® -3 | -4 ®\® -3 | 4.0 ®\® 2.1 | (1.0f+2.0fi) ®\® (3.0f+2.0fi); 516 256 64 -64 0.015625 -0.015625 18.3791736799526 0.264715-1.1922i 517 \end{cfa} 583 Integral exponentiation\index{exponentiation!unsigned integral} is performed with repeated multiplication\footnote{The multiplication computation is $O(\log y)$.} (or shifting if the exponent is 2). 584 Overflow from large exponents or negative exponents return zero. 585 Floating exponentiation\index{exponentiation!floating} is performed using \Index{logarithm}s\index{exponentiation!logarithm}, so the exponent cannot be negative. 586 \begin{cfa} 587 sout | 1 ®\® 0 | 1 ®\® 1 | 2 ®\® 8 | -4 ®\® 3 | 5 ®\® 3 | 5 ®\® 32 | 5L ®\® 32 | 5L ®\® 64 | -4 ®\® -3 | -4.0 ®\® -3 | 4.0 ®\® 2.1 588 | (1.0f+2.0fi) ®\® (3.0f+2.0fi); 589 1 1 256 -64 125 ®0® 3273344365508751233 ®0® ®0® -0.015625 18.3791736799526 0.264715-1.1922i 590 \end{cfa} 591 Note, ©5 ®\® 32© and ©5L ®\® 64© overflow, and ©-4 ®\® -3© is a fraction but stored in an integer so all three computations generate an integral zero. 518 592 Parenthesis are necessary for complex constants or the expression is parsed as ©1.0f+®(®2.0fi \ 3.0f®)®+2.0fi©. 519 The exponentiation operator is available for all the basic types, but for user-defined types, only the integral-computation versions are available. 520 For returning an integral value, the user type ©T© must define multiplication, ©*©, and one, ©1©; 521 for returning a floating value, an additional divide of type ©T© into a ©double© returning a ©double© (©double ?/?( double, T )©) is necessary for negative exponents. 593 The exponentiation operator is available for all the basic types, but for user-defined types, only the integral-computation version is available. 594 \begin{cfa} 595 forall( otype OT | { void ?{}( OT & this, one_t ); OT ?*?( OT, OT ); } ) 596 OT ?®\®?( OT ep, unsigned int y ); 597 forall( otype OT | { void ?{}( OT & this, one_t ); OT ?*?( OT, OT ); } ) 598 OT ?®\®?( OT ep, unsigned long int y ); 599 \end{cfa} 600 The user type ©T© must define multiplication, one, ©1©, and, ©*©. 522 601 523 602 … … 549 628 \subsection{Loop Control} 550 629 551 The ©for©/©while©/©do-while© loop-control allows empty or simplified ranges. 630 The ©for©/©while©/©do-while© loop-control allows empty or simplified ranges (see Figure~\ref{f:LoopControlExamples}). 631 \begin{itemize} 632 \item 552 633 An empty conditional implies ©1©. 553 The up-to range ©~©\index{~@©~©} means exclusive range [M,N); 554 the up-to range ©~=©\index{~=@©~=©} means inclusive range [M,N]. 555 The down-to range ©-~©\index{-~@©-~©} means exclusive range [N,M); 556 the down-to range ©-~=©\index{-~=@©-~=©} means inclusive range [N,M]. 634 \item 635 The up-to range ©~©\index{~@©~©} means exclusive range [M,N). 636 \item 637 The up-to range ©~=©\index{~=@©~=©} means inclusive range [M,N]. 638 \item 639 The down-to range ©-~©\index{-~@©-~©} means exclusive range [N,M). 640 \item 641 The down-to range ©-~=©\index{-~=@©-~=©} means inclusive range [N,M]. 642 \item 643 ©@© means put nothing in this field. 644 \item 557 645 ©0© is the implicit start value; 646 \item 558 647 ©1© is the implicit increment value. 648 \item 559 649 The up-to range uses ©+=© for increment; 560 the down-to range uses ©-=© for decrement. 650 \item 651 The down-to range uses ©-=© for decrement. 652 \item 561 653 The loop index is polymorphic in the type of the start value or comparison value when start is implicitly ©0©. 654 \end{itemize} 655 656 \begin{figure} 562 657 \begin{cquote} 563 \begin{tabular}{@{}l l|l@{}}564 \multicolumn{ 2}{c|}{loop control} & \multicolumn{1}{c}{output} \\658 \begin{tabular}{@{}l|l@{}} 659 \multicolumn{1}{c|}{loop control} & \multicolumn{1}{c}{output} \\ 565 660 \hline 566 661 \begin{cfa} 567 while ®()® { sout | "empty"; break; } 568 do { sout | "empty"; break; } while ®()®; 569 for ®()® { sout | "empty"; break; } 570 for ( ®0® ) { sout | "A"; } 571 for ( ®1® ) { sout | "A"; } 572 for ( ®10® ) { sout | "A"; } 573 for ( ®1 ~= 10 ~ 2® ) { sout | "B"; } 574 for ( ®10 -~= 1 ~ 2® ) { sout | "C"; } 575 for ( ®0.5 ~ 5.5® ) { sout | "D"; } 576 for ( ®5.5 -~ 0.5® ) { sout | "E"; } 577 for ( ®i; 10® ) { sout | i; } 578 for ( ®i; 1 ~= 10 ~ 2® ) { sout | i; } 579 for ( ®i; 10 -~= 1 ~ 2® ) { sout | i; } 580 for ( ®i; 0.5 ~ 5.5® ) { sout | i; } 581 for ( ®i; 5.5 -~ 0.5® ) { sout | i; } 582 for ( ®ui; 2u ~= 10u ~ 2u® ) { sout | ui; } 583 for ( ®ui; 10u -~= 2u ~ 2u® ) { sout | ui; } 662 sout | nlOff; 663 while ®()® { sout | "empty"; break; } sout | nl; 664 do { sout | "empty"; break; } while ®()®; sout | nl; 665 for ®()® { sout | "empty"; break; } sout | nl; 666 for ( ®0® ) { sout | "A"; } sout | "zero" | nl; 667 for ( ®1® ) { sout | "A"; } sout | nl; 668 for ( ®10® ) { sout | "A"; } sout | nl; 669 for ( ®1 ~= 10 ~ 2® ) { sout | "B"; } sout | nl; 670 for ( ®10 -~= 1 ~ 2® ) { sout | "C"; } sout | nl; 671 for ( ®0.5 ~ 5.5® ) { sout | "D"; } sout | nl; 672 for ( ®5.5 -~ 0.5® ) { sout | "E"; } sout | nl; 673 for ( ®i; 10® ) { sout | i; } sout | nl; 674 for ( ®i; 1 ~= 10 ~ 2® ) { sout | i; } sout | nl; 675 for ( ®i; 10 -~= 1 ~ 2® ) { sout | i; } sout | nl; 676 for ( ®i; 0.5 ~ 5.5® ) { sout | i; } sout | nl; 677 for ( ®i; 5.5 -~ 0.5® ) { sout | i; } sout | nl; 678 for ( ®ui; 2u ~= 10u ~ 2u® ) { sout | ui; } sout | nl; 679 for ( ®ui; 10u -~= 2u ~ 2u® ) { sout | ui; } sout | nl; 584 680 enum { N = 10 }; 585 for ( ®N® ) { sout | "N"; } 586 for ( ®i; N® ) { sout | i; } 587 for ( ®i; N -~ 0® ) { sout | i; } 681 for ( ®N® ) { sout | "N"; } sout | nl; 682 for ( ®i; N® ) { sout | i; } sout | nl; 683 for ( ®i; N -~ 0® ) { sout | i; } sout | nl; 588 684 const int start = 3, comp = 10, inc = 2; 589 for ( ®i; start ~ comp ~ inc + 1® ) { sout | i; } 685 for ( ®i; start ~ comp ~ inc + 1® ) { sout | i; } sout | nl; 686 for ( ®i; 1 ~ @® ) { if ( i > 10 ) break; 687 sout | i; } sout | nl; 688 for ( ®i; 10 -~ @® ) { if ( i < 0 ) break; 689 sout | i; } sout | nl; 690 for ( ®i; 2 ~ @ ~ 2® ) { if ( i > 10 ) break; 691 sout | i; } sout | nl; 692 for ( ®i; 2.1 ~ @ ~ @® ) { if ( i > 10.5 ) break; 693 sout | i; i += 1.7; } sout | nl; 694 for ( ®i; 10 -~ @ ~ 2® ) { if ( i < 0 ) break; 695 sout | i; } sout | nl; 696 for ( ®i; 12.1 ~ @ ~ @® ) { if ( i < 2.5 ) break; 697 sout | i; i -= 1.7; } sout | nl; 698 for ( ®i; 5 : j; -5 ~ @® ) { sout | i | j; } sout | nl; 699 for ( ®i; 5 : j; -5 -~ @® ) { sout | i | j; } sout | nl; 700 for ( ®i; 5 : j; -5 ~ @ ~ 2® ) { sout | i | j; } sout | nl; 701 for ( ®i; 5 : j; -5 -~ @ ~ 2® ) { sout | i | j; } sout | nl; 702 for ( ®j; -5 ~ @ : i; 5® ) { sout | i | j; } sout | nl; 703 for ( ®j; -5 -~ @ : i; 5® ) { sout | i | j; } sout | nl; 704 for ( ®j; -5 ~ @ ~ 2 : i; 5® ) { sout | i | j; } sout | nl; 705 for ( ®j; -5 -~ @ ~ 2 : i; 5® ) { sout | i | j; } sout | nl; 706 for ( ®j; -5 -~ @ ~ 2 : i; 5 : k; 1.5 ~ @® ) { 707 sout | i | j | k; } sout | nl; 708 for ( ®j; -5 -~ @ ~ 2 : k; 1.5 ~ @ : i; 5® ) { 709 sout | i | j | k; } sout | nl; 710 for ( ®k; 1.5 ~ @ : j; -5 -~ @ ~ 2 : i; 5® ) { 711 sout | i | j | k; } sout | nl; 590 712 \end{cfa} 591 713 & 592 714 \begin{cfa} 593 sout | nl; 594 sout | nl; 595 sout | nl; 596 sout | "zero" | nl; 597 sout | nl; 598 sout | nl; 599 sout | nl; 600 sout | nl; 601 sout | nl; 602 sout | nl; 603 sout | nl; 604 sout | nl; 605 sout | nl; 606 sout | nl; 607 sout | nl; 608 sout | nl; 609 sout | nl | nl; 610 611 sout | nl; 612 sout | nl; 613 sout | nl | nl; 614 615 sout | nl; 616 \end{cfa} 617 & 618 \begin{cfa} 715 619 716 empty 620 717 empty … … 640 737 641 738 3 6 9 739 740 1 2 3 4 5 6 7 8 9 10 741 742 10 9 8 7 6 5 4 3 2 1 0 743 744 2 4 6 8 10 745 746 2.1 3.8 5.5 7.2 8.9 747 748 10 8 6 4 2 0 749 750 12.1 10.4 8.7 7 5.3 3.6 751 0 -5 1 -4 2 -3 3 -2 4 -1 752 0 -5 1 -6 2 -7 3 -8 4 -9 753 0 -5 1 -3 2 -1 3 1 4 3 754 0 -5 1 -7 2 -9 3 -11 4 -13 755 0 -5 1 -4 2 -3 3 -2 4 -1 756 0 -5 1 -6 2 -7 3 -8 4 -9 757 0 -5 1 -3 2 -1 3 1 4 3 758 0 -5 1 -7 2 -9 3 -11 4 -13 759 760 0 -5 1.5 1 -7 2.5 2 -9 3.5 3 -11 4.5 4 -13 5.5 761 762 0 -5 1.5 1 -7 2.5 2 -9 3.5 3 -11 4.5 4 -13 5.5 763 764 0 -5 1.5 1 -7 2.5 2 -9 3.5 3 -11 4.5 4 -13 5.5 642 765 \end{cfa} 643 766 \end{tabular} 644 767 \end{cquote} 768 \caption{Loop Control Examples} 769 \label{f:LoopControlExamples} 770 \end{figure} 645 771 646 772 … … 1320 1446 \end{cfa} 1321 1447 Essentially, the return type is wrapped around the routine name in successive layers (like an \Index{onion}). 1322 While attempting to make the two contexts consistent is a laudable goal, it has not worked out in practice. 1448 While attempting to make the two contexts consistent is a laudable goal, it has not worked out in practice, even though Dennis Richie believed otherwise: 1449 \begin{quote} 1450 In spite of its difficulties, I believe that the C's approach to declarations remains plausible, and am comfortable with it; it is a useful unifying principle.~\cite[p.~12]{Ritchie93} 1451 \end{quote} 1323 1452 1324 1453 \CFA provides its own type, variable and routine declarations, using a different syntax.
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