99 lines
6.8 KiB
Factor
99 lines
6.8 KiB
Factor
USING: definitions help.markup help.syntax kernel parser
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quotations source-files stack-checker.errors words ;
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IN: compiler.units
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ARTICLE: "compilation-units-internals" "Compilation units internals"
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"These words do not need to be called directly, and only serve to support the implementation."
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$nl
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"Compiling a set of words:"
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{ $subsections compile }
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"Words called to associate a definition with a compilation unit and a source file location:"
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{ $subsections
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remember-definition
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remember-class
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}
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"Forward reference checking (see " { $link "definition-checking" } "):"
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{ $subsections forward-reference? }
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"A hook to be called at the end of the compilation unit. If the optimizing compiler is loaded, this compiles new words with the " { $link "compiler" } ":"
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{ $subsections recompile }
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"Low-level compiler interface exported by the Factor VM:"
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{ $subsections modify-code-heap } ;
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ARTICLE: "compilation-units" "Compilation units"
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"A " { $emphasis "compilation unit" } " scopes a group of related definitions. They are compiled and entered into the system in one atomic operation."
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$nl
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"When a source file is being parsed, all definitions are part of a single compilation unit, unless the " { $link POSTPONE: << } " parsing word is used to create nested compilation units."
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$nl
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"Words defined in a compilation unit may not be called until the compilation unit is finished. The parser detects this case for parsing words and throws a " { $link staging-violation } ". Similarly, an attempt to use a macro from a word defined in the same compilation unit will throw a " { $link transform-expansion-error } ". Calling any other word from within its own compilation unit throws an " { $link undefined } " error."
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$nl
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"This means that parsing words and macros generally cannot be used in the same source file as they are defined. There are two means of getting around this:"
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{ $list
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{ "The simplest way is to split off the parsing words and macros into sub-vocabularies; perhaps suffixed by " { $snippet ".syntax" } " and " { $snippet ".macros" } "." }
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{ "Alternatively, nested compilation units can be created using " { $link "syntax-immediate" } "." }
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}
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"Parsing words which create new definitions at parse time will implicitly add them to the compilation unit of the current source file."
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$nl
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"Code which creates new definitions at run time will need to explicitly create a compilation unit with a combinator. There is an additional combinator used by the parser to implement " { $link "syntax-immediate" } "."
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{ $subsections with-compilation-unit with-nested-compilation-unit }
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"Additional topics:"
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{ $subsections "compilation-units-internals" } ;
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ABOUT: "compilation-units"
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HELP: redefine-error
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{ $values { "definition" "a definition specifier" } }
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{ $description "Throws a " { $link redefine-error } "." }
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{ $error-description "Indicates that a single source file contains two definitions for the same artifact, one of which shadows the other. This is an error since it indicates a likely mistake, such as two words accidentally named the same by the developer; the error is restartable." } ;
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HELP: remember-definition
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{ $values { "definition" "a definition specifier" } { "loc" "a " { $snippet "{ path line# }" } " pair" } }
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{ $description "Saves the location of a definition and associates this definition with the current source file." } ;
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HELP: old-definitions
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{ $var-description "Stores a pair of sets where the members form the set of definitions which were defined by " { $link file } " the most recent time it was loaded." } ;
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HELP: new-definitions
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{ $var-description "Stores a pair of sets where the members form the set of definitions which were defined so far by the current parsing of " { $link file } "." } ;
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HELP: with-compilation-unit
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{ $values { "quot" quotation } }
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{ $description "Calls a quotation in a new compilation unit. The quotation can define new words and classes, as well as forget words. When the quotation returns, any changed words are recompiled, and changes are applied atomically." }
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{ $notes "Calls to " { $link with-compilation-unit } " may be nested."
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$nl
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"The parser wraps every source file in a compilation unit, so parsing words may define new words without having to perform extra work; to define new words at any other time, you must wrap your defining code with this combinator."
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$nl
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"Since compilation is relatively expensive, you should try to batch up as many definitions into one compilation unit as possible." } ;
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HELP: with-nested-compilation-unit
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{ $values { "quot" quotation } }
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{ $description "Calls a quotation in a new compilation unit. The only difference between this word and " { $link with-compilation-unit } " is that variables used by the parser to associate definitions with source files are not rebound." }
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{ $notes "This word is used by " { $link "syntax-immediate" } " to ensure that definitions in nested blocks are correctly recorded. User code should not depend on parser internals in such a way that calling this combinator is required." } ;
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HELP: recompile
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{ $values { "words" "a sequence of words" } { "alist" "an association list mapping words to compiled definitions" } }
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{ $contract "Internal word which compiles words. Called at the end of " { $link with-compilation-unit } "." } ;
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HELP: no-compilation-unit
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{ $values { "word" word } }
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{ $description "Throws a " { $link no-compilation-unit } " error." }
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{ $error-description "Thrown when an attempt is made to define a word outside of a " { $link with-compilation-unit } " combinator." } ;
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HELP: modify-code-heap
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{ $values { "alist" "an association list with words as keys" } { "update-existing?" boolean } { "reset-pics?" boolean } }
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{ $description "Lowest-level primitive for defining words. Associates words with code blocks in the code heap."
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$nl
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"The alist maps words to one of the following:"
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{ $list
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{ "a quotation - in this case, the quotation is compiled with the non-optimizing compiler and the word will call the quotation when executed." }
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{ "a 6-element array " { $snippet "{ parameters literals relocation labels code stack-frame-size }" } " - in this case, a code heap block is allocated with the given data and the word will call the code block when executed. This is used by the optimizing compiler." }
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}
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"If any of the redefined words may already be referenced by other words in the code heap, from outside of the compilation unit, then a scan of the code heap must be performed to update all word call sites. Passing " { $link t } " as the " { $snippet "update-existing?" } " parameter enables this code path."
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$nl
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"If classes, methods or generic words were redefined, then inline cache call sites need to be updated as well. Passing " { $link t } " as the " { $snippet "reset-pics?" } " parameter enables this code path."
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}
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{ $notes "This word is called at the end of " { $link with-compilation-unit } "." } ;
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HELP: compile
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{ $values { "words" "a sequence of words" } }
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{ $description "Compiles a set of words." } ;
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