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74-553: Clang ( / ˈ k l æ ŋ / ) is a compiler front end for the programming languages C , C++ , Objective-C , Objective-C++ , and the software frameworks OpenMP , OpenCL , RenderScript , CUDA , SYCL , and HIP . It acts as a drop-in replacement for the GNU Compiler Collection (GCC), supporting most of its compiling flags and unofficial language extensions. It includes a static analyzer , and several code analysis tools. Clang operates in tandem with

148-533: A basic block , to whole procedures, or even the whole program. There is a trade-off between the granularity of the optimizations and the cost of compilation. For example, peephole optimizations are fast to perform during compilation but only affect a small local fragment of the code, and can be performed independently of the context in which the code fragment appears. In contrast, interprocedural optimization requires more compilation time and memory space, but enable optimizations that are only possible by considering

222-412: A concrete syntax tree (CST, parse tree) and then transforming it into an abstract syntax tree (AST, syntax tree). In some cases additional phases are used, notably line reconstruction and preprocessing, but these are rare. The main phases of the front end include the following: The middle end, also known as optimizer, performs optimizations on the intermediate representation in order to improve

296-408: A parser for each possible language. This can result in a text rendering system displaying somewhat inaccurate syntax highlighting and in some cases performing slowly. A solution used by text editors to overcome this problem is not always parsing the whole file but rather just the visible area, sometimes scanning backwards in the text up to a limited number of lines for "syncing". On the other hand,

370-422: A PDP-7 in B. Unics eventually became spelled Unix. Bell Labs started the development and expansion of C based on B and BCPL. The BCPL compiler had been transported to Multics by Bell Labs and BCPL was a preferred language at Bell Labs. Initially, a front-end program to Bell Labs' B compiler was used while a C compiler was developed. In 1971, a new PDP-11 provided the resource to define extensions to B and rewrite

444-437: A Production Quality Compiler (PQC) from formal definitions of source language and the target. PQCC tried to extend the term compiler-compiler beyond the traditional meaning as a parser generator (e.g., Yacc ) without much success. PQCC might more properly be referred to as a compiler generator. PQCC research into code generation process sought to build a truly automatic compiler-writing system. The effort discovered and designed

518-401: A compile- link - debug workflow; integrating it with other tools is not always easy. For instance, GCC uses a step called fold that is key to the overall compile process, which has the side effect of translating the code tree into a form that looks unlike the original source code. If an error is found during or after the fold step, it can be difficult to translate that back into one location in

592-405: A compiler up into small programs is a technique used by researchers interested in producing provably correct compilers. Proving the correctness of a set of small programs often requires less effort than proving the correctness of a larger, single, equivalent program. Regardless of the exact number of phases in the compiler design, the phases can be assigned to one of three stages. The stages include

666-432: A component of an IDE (VADS, Eclipse, Ada Pro). The interrelationship and interdependence of technologies grew. The advent of web services promoted growth of web languages and scripting languages. Scripts trace back to the early days of Command Line Interfaces (CLI) where the user could enter commands to be executed by the system. User Shell concepts developed with languages to write shell programs. Early Windows designs offered

740-553: A front end, a middle end, and a back end. This front/middle/back-end approach makes it possible to combine front ends for different languages with back ends for different CPUs while sharing the optimizations of the middle end. Practical examples of this approach are the GNU Compiler Collection , Clang ( LLVM -based C/C++ compiler), and the Amsterdam Compiler Kit , which have multiple front-ends, shared optimizations and multiple back-ends. The front end analyzes

814-527: A grammar for the language, though in more complex cases these require manual modification. The lexical grammar and phrase grammar are usually context-free grammars , which simplifies analysis significantly, with context-sensitivity handled at the semantic analysis phase. The semantic analysis phase is generally more complex and written by hand, but can be partially or fully automated using attribute grammars . These phases themselves can be further broken down: lexing as scanning and evaluating, and parsing as building

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888-692: A mixed compile time and program performance benchmark. However, by 2019, Clang is significantly slower at compiling the Linux Kernel than GCC while remaining slightly faster at compiling LLVM. While Clang has historically been faster than GCC at compiling, the output quality has lagged behind. As of 2014, performance of Clang-compiled programs lagged behind performance of the GCC-compiled program, sometimes by large factors (up to 5.5x), replicating earlier reports of slower performance. Both compilers have evolved to increase their performance since then, with

962-557: A new compiler front end which supports C, Objective-C and C++. In July 2007, the project received the approval for becoming open-source. Clang works in tandem with LLVM. The combination of Clang and LLVM provides most of the toolchain for replacing the GCC stack . One of Clang's main goals is to provide a library-based architecture, so that the compiler could interoperate with other tools that interact with source code, such as integrated development environments (IDE). In contrast, GCC works in

1036-432: A result, compilers were split up into smaller programs which each made a pass over the source (or some representation of it) performing some of the required analysis and translations. The ability to compile in a single pass has classically been seen as a benefit because it simplifies the job of writing a compiler and one-pass compilers generally perform compilations faster than multi-pass compilers . Thus, partly driven by

1110-431: A simple batch programming capability. The conventional transformation of these language used an interpreter. While not widely used, Bash and Batch compilers have been written. More recently sophisticated interpreted languages became part of the developers tool kit. Modern scripting languages include PHP, Python, Ruby and Lua. (Lua is widely used in game development.) All of these have interpreter and compiler support. "When

1184-492: Is Open64 , which is used by many organizations for research and commercial purposes. Due to the extra time and space needed for compiler analysis and optimizations, some compilers skip them by default. Users have to use compilation options to explicitly tell the compiler which optimizations should be enabled. The back end is responsible for the CPU architecture specific optimizations and for code generation . The main phases of

1258-473: Is a comparison of a snippet of C code: Below is another snippet of syntax highlighted C++ code: In the C++ example, the editor has recognized the keywords const , auto , int , and for . The comment at the beginning is also highlighted in a specific manner to distinguish it from working code. The ideas of syntax highlighting overlap significantly with those of syntax-directed editors . One of

1332-518: Is a low priority for GCC developers. As such, GCC does not integrate smoothly into Apple's integrated development environment (IDE). Finally, GCC's license agreement, the GNU General Public License (GPL) version 3 , requires developers who distribute extensions or modified versions of GCC to make their source code available, but LLVM's permissive software license doesn't require this. For these reasons, Apple developed Clang,

1406-613: Is also commercial support, for example, AdaCore, was founded in 1994 to provide commercial software solutions for Ada. GNAT Pro includes the GNU GCC based GNAT with a tool suite to provide an integrated development environment . High-level languages continued to drive compiler research and development. Focus areas included optimization and automatic code generation. Trends in programming languages and development environments influenced compiler technology. More compilers became included in language distributions (PERL, Java Development Kit) and as

1480-446: Is favored due to its modularity and separation of concerns . Most commonly, the frontend is broken into three phases: lexical analysis (also known as lexing or scanning), syntax analysis (also known as scanning or parsing), and semantic analysis . Lexing and parsing comprise the syntactic analysis (word syntax and phrase syntax, respectively), and in simple cases, these modules (the lexer and parser) can be automatically generated from

1554-417: Is primarily used for programs that translate source code from a high-level programming language to a low-level programming language (e.g. assembly language , object code , or machine code ) to create an executable program. There are many different types of compilers which produce output in different useful forms. A cross-compiler produces code for a different CPU or operating system than

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1628-557: Is suitable for printing or for importing into word-processing and other kinds of text-formatting software; for instance as a HTML, colorized LaTeX, PostScript or RTF version of its syntax highlighting. There are several syntax highlighting libraries or "engines" that can be used in other applications, but are not complete programs in themselves, for example the Generic Syntax Highlighter (GeSHi) extension for PHP . For editors that support more than one language,

1702-612: Is under active development. Development versions of Flang were in progress as of October 2023 and could be downloaded from the LLVM Project. Clang is compatible with GCC. Its command-line interface shares many of GCC's flags and options. Clang implements many GNU language extensions and compiler intrinsics , some of which are purely for compatibility. For example, even though Clang implements atomic intrinsics which correspond exactly with C11 atomics , it also implements GCC's __sync_* intrinsics for compatibility with GCC and

1776-748: The C++ Standard Library (libstdc++). Clang also maintains application binary interface (ABI) compatibility with GCC-generated object code . In practice, Clang is a drop-in replacement for GCC. Clang's developers aim to reduce memory footprint and increase compiling speed compared to other compilers, such as GCC. In October 2007, they report that Clang compiled the Carbon libraries more than twice as fast as GCC, while using about one-sixth GCC's memory and disk space. By 2011, Clang seemed to retain this advantage in compiler performance. As of mid-2014, Clang still consistently compiles faster than GCC in

1850-563: The LLVM compiler back end and has been a subproject of LLVM 2.6 and later. As with LLVM, it is free and open-source software under the Apache 2.0 software license . Its contributors include Apple , Microsoft , Google , ARM , Sony , Intel , and AMD . Clang 17, the latest major version of Clang as of October 2023, has full support for all published C++ standards up to C++17 , implements most features of C++20 , and has initial support for

1924-599: The (since 1995, object-oriented) programming language Ada . The Ada STONEMAN document formalized the program support environment (APSE) along with the kernel (KAPSE) and minimal (MAPSE). An Ada interpreter NYU/ED supported development and standardization efforts with the American National Standards Institute (ANSI) and the International Standards Organization (ISO). Initial Ada compiler development by

1998-587: The Early PL/I (EPL) compiler by Doug McIlory and Bob Morris from Bell Labs. EPL supported the project until a boot-strapping compiler for the full PL/I could be developed. Bell Labs left the Multics project in 1969, and developed a system programming language B based on BCPL concepts, written by Dennis Ritchie and Ken Thompson . Ritchie created a boot-strapping compiler for B and wrote Unics (Uniplexed Information and Computing Service) operating system for

2072-661: The Intellivision's Entertainment Computer System (ECS) peripheral, released in 1983. It would highlight different elements of BASIC programs and was implemented in an attempt to make it easier for beginners, especially children, to start writing code. Later, the Live Parsing Editor ( LEXX ) written for the VM operating system for the computerization of the Oxford English Dictionary in 1985

2146-528: The Sun 3/60 Solaris targeted to Motorola 68020 in an Army CECOM evaluation. There were soon many Ada compilers available that passed the Ada Validation tests. The Free Software Foundation GNU project developed the GNU Compiler Collection (GCC) which provides a core capability to support multiple languages and targets. The Ada version GNAT is one of the most widely used Ada compilers. GNAT is free but there

2220-670: The U.S. Military Services included the compilers in a complete integrated design environment along the lines of the STONEMAN document. Army and Navy worked on the Ada Language System (ALS) project targeted to DEC/VAX architecture while the Air Force started on the Ada Integrated Environment (AIE) targeted to IBM 370 series. While the projects did not provide the desired results, they did contribute to

2294-471: The University of Cambridge was originally developed as a compiler writing tool. Several compilers have been implemented, Richards' book provides insights to the language and its compiler. BCPL was not only an influential systems programming language that is still used in research but also provided a basis for the design of B and C languages. BLISS (Basic Language for Implementation of System Software)

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2368-420: The back end include the following: Syntax highlighting Syntax highlighting is a form of secondary notation , since the highlights are not part of the text meaning, but serve to reinforce it. Some editors also integrate syntax highlighting with other features, such as spell checking or code folding , as aids to editing which are external to the language. Syntax highlighting is one strategy to improve

2442-435: The basis of digital modern computing development during World War II. Primitive binary languages evolved because digital devices only understand ones and zeros and the circuit patterns in the underlying machine architecture. In the late 1940s, assembly languages were created to offer a more workable abstraction of the computer architectures. Limited memory capacity of early computers led to substantial technical challenges when

2516-433: The behavior of multiple functions simultaneously. Interprocedural analysis and optimizations are common in modern commercial compilers from HP , IBM , SGI , Intel , Microsoft , and Sun Microsystems . The free software GCC was criticized for a long time for lacking powerful interprocedural optimizations, but it is changing in this respect. Another open source compiler with full analysis and optimization infrastructure

2590-427: The code difficult to read. Called syntax decoration , some editors also display certain syntactical elements in more visually pleasing ways, for example by replacing a pointer operator like -> in source code by an actual arrow symbol (→), or changing text decoration clues like /italics/, *boldface*, or _underline_ in source code comments by an actual italics , boldface , or underlined presentation. Below

2664-484: The compiler's output. Modular design of the compiler can offer source code indexing, syntax checking, and other features normally associated with rapid application development systems. The parse tree is also more suitable for supporting automated code refactoring , as it directly represents the original source code. Clang compiles only C-like languages, such as C, C++, Objective-C, and Objective-C++. In many cases, Clang can replace GCC as needed, with no other effects on

2738-591: The compiler. By 1973 the design of C language was essentially complete and the Unix kernel for a PDP-11 was rewritten in C. Steve Johnson started development of Portable C Compiler (PCC) to support retargeting of C compilers to new machines. Object-oriented programming (OOP) offered some interesting possibilities for application development and maintenance. OOP concepts go further back but were part of LISP and Simula language science. Bell Labs became interested in OOP with

2812-404: The contrasting color of the text. Brace matching is another important feature with many popular editors. This makes it simple to see if a brace has been left out or locate the match of the brace the cursor is on by highlighting the pair in a different color. A study published in the conference PPIG evaluated the effects of syntax highlighting on the comprehension of short programs, finding that

2886-407: The development of C++ . C++ was first used in 1980 for systems programming. The initial design leveraged C language systems programming capabilities with Simula concepts. Object-oriented facilities were added in 1983. The Cfront program implemented a C++ front-end for C84 language compiler. In subsequent years several C++ compilers were developed as C++ popularity grew. In many application domains,

2960-551: The development of compiler technology: Early operating systems and software were written in assembly language. In the 1960s and early 1970s, the use of high-level languages for system programming was still controversial due to resource limitations. However, several research and industry efforts began the shift toward high-level systems programming languages, for example, BCPL , BLISS , B , and C . BCPL (Basic Combined Programming Language) designed in 1966 by Martin Richards at

3034-424: The development of high-level languages followed naturally from the capabilities offered by digital computers. High-level languages are formal languages that are strictly defined by their syntax and semantics which form the high-level language architecture. Elements of these formal languages include: The sentences in a language may be defined by a set of rules called a grammar. Backus–Naur form (BNF) describes

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3108-424: The early days, the approach taken to compiler design was directly affected by the complexity of the computer language to be processed, the experience of the person(s) designing it, and the resources available. Resource limitations led to the need to pass through the source code more than once. A compiler for a relatively simple language written by one person might be a single, monolithic piece of software. However, as

3182-444: The editor often displays code during its creation, while it is incomplete or incorrect, and the strict parsers (like ones used in compilers) would fail to parse the code most of the time. Some modern, language-specific IDEs (in contrast to text editors) perform full language parsing which results in very accurate understanding of code. An extension of syntax highlighting was called "semantic highlighting" in 2009 by David Nolden for

3256-491: The field of compiling began in the late 50s, its focus was limited to the translation of high-level language programs into machine code ... The compiler field is increasingly intertwined with other disciplines including computer architecture, programming languages, formal methods, software engineering, and computer security." The "Compiler Research: The Next 50 Years" article noted the importance of object-oriented languages and Java. Security and parallel computing were cited among

3330-464: The first (algorithmic) programming language for computers called Plankalkül ("Plan Calculus"). Zuse also envisioned a Planfertigungsgerät ("Plan assembly device") to automatically translate the mathematical formulation of a program into machine-readable punched film stock . While no actual implementation occurred until the 1970s, it presented concepts later seen in APL designed by Ken Iverson in

3404-423: The first compilers were designed. Therefore, the compilation process needed to be divided into several small programs. The front end programs produce the analysis products used by the back end programs to generate target code. As computer technology provided more resources, compiler designs could align better with the compilation process. It is usually more productive for a programmer to use a high-level language, so

3478-559: The first pass needs to gather information about declarations appearing after statements that they affect, with the actual translation happening during a subsequent pass. The disadvantage of compiling in a single pass is that it is not possible to perform many of the sophisticated optimizations needed to generate high quality code. It can be difficult to count exactly how many passes an optimizing compiler makes. For instance, different phases of optimization may analyse one expression many times but only analyse another expression once. Splitting

3552-401: The first such editors for code was Wilfred Hansen's 1969 code editor, Emily. It provided advanced language-independent code completion facilities, and unlike modern editors with syntax highlighting, actually made it impossible to create syntactically incorrect programs. In 1982, Anita H. Klock and Jan B. Chodak filed a patent for the first known syntax highlighting system, which was used in

3626-933: The form of expressions without a change of language; and compiler-compilers , compilers that produce compilers (or parts of them), often in a generic and reusable way so as to be able to produce many differing compilers. A compiler is likely to perform some or all of the following operations, often called phases: preprocessing , lexical analysis , parsing , semantic analysis ( syntax-directed translation ), conversion of input programs to an intermediate representation , code optimization and machine specific code generation . Compilers generally implement these phases as modular components, promoting efficient design and correctness of transformations of source input to target output. Program faults caused by incorrect compiler behavior can be very difficult to track down and work around; therefore, compiler implementers invest significant effort to ensure compiler correctness . Compilers are not

3700-454: The future research targets. A compiler implements a formal transformation from a high-level source program to a low-level target program. Compiler design can define an end-to-end solution or tackle a defined subset that interfaces with other compilation tools e.g. preprocessors, assemblers, linkers. Design requirements include rigorously defined interfaces both internally between compiler components and externally between supporting toolsets. In

3774-673: The gap narrowing: libclang provides a C interface, providing a relatively small API. Exposed functionality includes: parsing source code into an AST , loading ASTs, traversing the AST, associating source locations with elements within the AST. This table presents only significant steps and releases in Clang history. Compiler front end In computing , a compiler is a computer program that translates computer code written in one programming language (the source language) into another language (the target language). The name "compiler"

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3848-421: The idea of using a higher-level language quickly caught on. Because of the expanding functionality supported by newer programming languages and the increasing complexity of computer architectures, compilers became more complex. DARPA (Defense Advanced Research Projects Agency) sponsored a compiler project with Wulf's CMU research team in 1970. The Production Quality Compiler-Compiler PQCC design would produce

3922-434: The late 1950s. APL is a language for mathematical computations. Between 1949 and 1951, Heinz Rutishauser proposed Superplan , a high-level language and automatic translator. His ideas were later refined by Friedrich L. Bauer and Klaus Samelson . High-level language design during the formative years of digital computing provided useful programming tools for a variety of applications: Compiler technology evolved from

3996-408: The need for a strictly defined transformation of the high-level source program into a low-level target program for the digital computer. The compiler could be viewed as a front end to deal with the analysis of the source code and a back end to synthesize the analysis into the target code. Optimization between the front end and back end could produce more efficient target code. Some early milestones in

4070-475: The one on which the cross-compiler itself runs. A bootstrap compiler is often a temporary compiler, used for compiling a more permanent or better optimised compiler for a language. Related software include decompilers , programs that translate from low-level languages to higher level ones; programs that translate between high-level languages, usually called source-to-source compilers or transpilers ; language rewriters , usually programs that translate

4144-570: The only language processor used to transform source programs. An interpreter is computer software that transforms and then executes the indicated operations. The translation process influences the design of computer languages, which leads to a preference of compilation or interpretation. In theory, a programming language can have both a compiler and an interpreter. In practice, programming languages tend to be associated with just one (a compiler or an interpreter). Theoretical computing concepts developed by scientists, mathematicians, and engineers formed

4218-400: The open-source C++ IDE KDevelop . For example, semantic highlighting may give local variables unique distinct colors to improve the comprehensibility of code. In 2014 the idea of colored local variables was further popularized due to a blog post by Evan Brooks, and after that, the idea was transferred to other popular IDEs like Visual Studio , Xcode , and others. Color in a user interface

4292-523: The original source. Besides, vendors using the GCC stack within IDEs must use separate tools to index the code, to provide features like syntax highlighting and intelligent code completion . Clang retains more information during the compiling process than GCC, and preserves the overall form of the original code, making it easier to map errors back into the original source. Clang's error reports are more detailed, specific, and machine-readable, so IDEs can index

4366-667: The overall effort on Ada development. Other Ada compiler efforts got underway in Britain at the University of York and in Germany at the University of Karlsruhe. In the U. S., Verdix (later acquired by Rational) delivered the Verdix Ada Development System (VADS) to the Army. VADS provided a set of development tools including a compiler. Unix/VADS could be hosted on a variety of Unix platforms such as DEC Ultrix and

4440-511: The performance and the quality of the produced machine code. The middle end contains those optimizations that are independent of the CPU architecture being targeted. The main phases of the middle end include the following: Compiler analysis is the prerequisite for any compiler optimization, and they tightly work together. For example, dependence analysis is crucial for loop transformation . The scope of compiler analysis and optimizations vary greatly; their scope may range from operating within

4514-646: The phase structure of the PQC. The BLISS-11 compiler provided the initial structure. The phases included analyses (front end), intermediate translation to virtual machine (middle end), and translation to the target (back end). TCOL was developed for the PQCC research to handle language specific constructs in the intermediate representation. Variations of TCOL supported various languages. The PQCC project investigated techniques of automated compiler construction. The design concepts proved useful in optimizing compilers and compilers for

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4588-399: The presence of syntax highlighting significantly reduces the time taken for a programmer to internalise the semantics of a program. Additionally, data gathered from an eye-tracker during the study suggested that syntax highlighting enables programmers to pay less attention to standard syntactic components such as keywords. Some text editors can also export the coloured markup in a format that

4662-411: The readability and context of the text; especially for code that spans several pages. The reader can easily ignore large sections of comments or code, depending on what they are looking for. Syntax highlighting also helps programmers find errors in their program. For example, most editors highlight string literals in a different color. Consequently, spotting a missing delimiter is much easier because of

4736-429: The resource limitations of early systems, many early languages were specifically designed so that they could be compiled in a single pass (e.g., Pascal ). In some cases, the design of a language feature may require a compiler to perform more than one pass over the source. For instance, consider a declaration appearing on line 20 of the source which affects the translation of a statement appearing on line 10. In this case,

4810-490: The source code to build an internal representation of the program, called the intermediate representation (IR). It also manages the symbol table , a data structure mapping each symbol in the source code to associated information such as location, type and scope. While the frontend can be a single monolithic function or program, as in a scannerless parser , it was traditionally implemented and analyzed as several phases, which may execute sequentially or concurrently. This method

4884-469: The source language grows in complexity the design may be split into a number of interdependent phases. Separate phases provide design improvements that focus development on the functions in the compilation process. Classifying compilers by number of passes has its background in the hardware resource limitations of computers. Compiling involves performing much work and early computers did not have enough memory to contain one program that did all of this work. As

4958-440: The syntax of "sentences" of a language. It was developed by John Backus and used for the syntax of Algol 60 . The ideas derive from the context-free grammar concepts by linguist Noam Chomsky . "BNF and its extensions have become standard tools for describing the syntax of programming notations. In many cases, parts of compilers are generated automatically from a BNF description." Between 1942 and 1945, Konrad Zuse designed

5032-508: The toolchain as a whole. It supports most of the commonly used GCC options. A Fortran project, Flang was in-progress in 2022. However, for other languages, such as Ada , LLVM remains dependent on GCC or another compiler front end. The Flang project by Nvidia and The Portland Group adds Fortran support. Flang is LLVM's Fortran frontend. It is often referred to as "LLVM Flang" to differentiate itself from "Classic Flang" – these are two separate and independent Fortran compilers. "LLVM Flang"

5106-581: The upcoming C++23 standard. Since v16.0.0, Clang compiles C++ using the GNU++17 dialect by default, which includes features from the C++17 standard and conforming GNU extensions. In 2005, Apple Inc. made extensive use of LLVM in several commercial products, including the iOS SDK and Xcode 3.1. An OpenGL code compiler for OS X that converts OpenGL calls into more fundamental calls for graphics processing units (GPU) that do not support certain features,

5180-810: The user can usually specify the language of the text, such as C , LaTeX , HTML , or the text editor can automatically recognize it based on the file extension or by scanning contents of the file. This automatic language detection presents potential problems. For example, a user may want to edit a document containing: In these cases, it is not clear what language to use, and a document may not be highlighted or be highlighted incorrectly. Most editors with syntax highlighting allow different colors and text styles to be given to dozens of different lexical sub-elements of syntax. These include keywords, comments, control-flow statements, variables, and other elements. Programmers often heavily customize their settings in an attempt to show as much useful information as possible without making

5254-432: Was developed for a Digital Equipment Corporation (DEC) PDP-10 computer by W. A. Wulf's Carnegie Mellon University (CMU) research team. The CMU team went on to develop BLISS-11 compiler one year later in 1970. Multics (Multiplexed Information and Computing Service), a time-sharing operating system project, involved MIT , Bell Labs , General Electric (later Honeywell ) and was led by Fernando Corbató from MIT. Multics

5328-604: Was one of the first to use color syntax highlighting. Its live parsing capability allowed user-supplied parsers to be added to the editor, for text, programs, data file, etc. On microcomputers , MacPascal 1.0 (October 10, 1985) recognized Pascal syntax as it was typed and used font changes (e.g., bold for keywords) to highlight syntax on the monochrome compact Macintosh and automatically indented code to match its structure. Some text editors and code formatting tools perform syntax highlighting using pattern matching heuristics (e.g. Regular expressions ) rather than implementing

5402-451: Was one of the first uses of LLVM. This enabled Apple to support OpenGL on computers using Intel GMA chipsets, increasing performance on those machines. The LLVM project originally intended to use GCC 's front end. The GCC source code, however, is large and somewhat cumbersome; as one long-time GCC developer put it referring to LLVM, "Trying to make the hippo dance is not really a lot of fun". Besides, Apple software uses Objective-C , which

5476-470: Was written in the PL/I language developed by IBM and IBM User Group. IBM's goal was to satisfy business, scientific, and systems programming requirements. There were other languages that could have been considered but PL/I offered the most complete solution even though it had not been implemented. For the first few years of the Multics project, a subset of the language could be compiled to assembly language with

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