611 lines
35 KiB
Factor
611 lines
35 KiB
Factor
USING: help.markup help.syntax kernel sequences words
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math strings vectors quotations generic effects classes
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vocabs.loader definitions io vocabs source-files
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quotations namespaces ;
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IN: parser
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ARTICLE: "vocabulary-search-shadow" "Shadowing word names"
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"If adding a vocabulary to the search path results in a word in another vocabulary becoming inaccessible due to the new vocabulary defining a word with the same name, a message is printed to the " { $link stdio } " stream. Except when debugging suspected name clashes, these messages can be ignored."
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$nl
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"Here is an example where shadowing occurs:"
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{ $code
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"IN: foe"
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"USING: sequences io ;"
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""
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": append"
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" #! Prints a message, then calls sequences::append."
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" \"foe::append calls sequences::append\" print append ;"
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""
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"IN: fee"
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""
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": append"
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" #! Infinite recursion! Calls fee::append."
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" \"fee::append calls fee::append\" print append ;"
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""
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"USE: foe"
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""
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": append"
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" #! Redefining fee::append to call foe::append."
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" \"fee::append calls foe::append\" print append ;"
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""
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"\"1234\" \"5678\" append print"
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}
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"When placed in a source file and run, the above code produces the following output:"
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{ $code
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"fee::append calls foe::append"
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"foe::append calls sequences::append"
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"12345678"
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} ;
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ARTICLE: "vocabulary-search-errors" "Word lookup errors"
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"If the parser cannot not find a word in the current vocabulary search path, it attempts to look for the word in all loaded vocabularies. Then, one of three things happen:"
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{ $list
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{ "If there are no words having this name at all, an error is thrown and parsing stops." }
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{ "If there is exactly one vocabulary having a word with this name, the vocabulary is automatically added to the search path. This behavior is intended for interactive use and exploratory programming only, and production code should contain full " { $link POSTPONE: USING: } " declarations." }
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{ "If there is more than one vocabulary which contains a word with this name, a restartable error is thrown, with a restart for each vocabulary in question. The restarts add the vocabulary to the search path and continue parsing." }
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}
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"When writing a new vocabulary, one approach is to ignore " { $link POSTPONE: USING: } " declarations altogether, then to load the vocabulary and observe any parser notes and restarts and use this information to write the correct " { $link POSTPONE: USING: } " declaration." ;
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ARTICLE: "vocabulary-search" "Vocabulary search"
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"When the parser reads a token, it attempts to look up a word named by that token. The lookup is performed by searching each vocabulary in the search path, in order."
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$nl
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"For a source file the vocabulary search path starts off with two vocabularies:"
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{ $code "syntax\nscratchpad" }
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"The " { $vocab-link "syntax" } " vocabulary consists of a set of parsing words for reading Factor data and defining new words. The " { $vocab-link "scratchpad" } " vocabulary is the default vocabulary for new word definitions."
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$nl
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"At the interactive listener, the default search path contains many more vocabularies. Details on the default search path and parser invocation are found in " { $link "parser" } "."
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$nl
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"Three parsing words deal with the vocabulary search path:"
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{ $subsection POSTPONE: USE: }
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{ $subsection POSTPONE: USING: }
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{ $subsection POSTPONE: IN: }
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"Private words can be defined; note that this is just a convention and they can be called from other vocabularies anyway:"
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{ $subsection POSTPONE: <PRIVATE }
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{ $subsection POSTPONE: PRIVATE> }
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{ $subsection "vocabulary-search-errors" }
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{ $subsection "vocabulary-search-shadow" }
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{ $see-also "words" } ;
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ARTICLE: "reading-ahead" "Reading ahead"
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"Parsing words can consume input:"
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{ $subsection scan }
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{ $subsection scan-word }
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"For example, the " { $link POSTPONE: HEX: } " word uses this feature to read hexadecimal literals:"
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{ $see POSTPONE: HEX: }
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"It is defined in terms of a lower-level word that takes the numerical base on the data stack, but reads the number from the parser and then adds it to the parse tree:"
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{ $see parse-base }
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"Another simple example is the " { $link POSTPONE: \ } " word:"
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{ $see POSTPONE: \ } ;
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ARTICLE: "parsing-word-nest" "Nested structure"
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"Recall that the parser loop calls parsing words with an accumulator vector on the stack. The parser loop can be invoked recursively with a new, empty accumulator; the result can then be added to the original accumulator. This is how parsing words for object literals are implemented; object literals can nest arbitrarily deep."
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$nl
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"A simple example is the parsing word that reads a quotation:"
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{ $see POSTPONE: [ }
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"This word uses a utility word which recursively invokes the parser, reading objects into a new accumulator until an occurrence of " { $link POSTPONE: ] } ":"
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{ $subsection parse-literal }
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"There is another, lower-level word for reading nested structure, which is also useful when called directly:"
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{ $subsection parse-until }
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"Words such as " { $link POSTPONE: ] } " use a declaration which causes them to throw an error when an unpaired occurrence is encountered:"
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{ $subsection POSTPONE: delimiter }
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{ $see-also POSTPONE: { POSTPONE: H{ POSTPONE: V{ POSTPONE: W{ POSTPONE: T{ POSTPONE: } } ;
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ARTICLE: "defining-words" "Defining words"
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"Defining words add definitions to the dictionary without modifying the parse tree. The simplest example is the " { $link POSTPONE: SYMBOL: } " word."
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{ $see POSTPONE: SYMBOL: }
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"The key factor in the definition of " { $link POSTPONE: SYMBOL: } " is " { $link CREATE } ", which reads a token from the input and creates a word with that name. This word is then passed to " { $link define-symbol } "."
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{ $subsection CREATE }
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"Colon definitions are defined in a more elaborate way:"
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{ $subsection POSTPONE: : }
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"The " { $link POSTPONE: : } " word first calls " { $link CREATE } ", and then reads input until reaching " { $link POSTPONE: ; } " using a utility word:"
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{ $subsection parse-definition }
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"The " { $link POSTPONE: ; } " word is just a delimiter; an unpaired occurrence throws a parse error:"
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{ $see POSTPONE: ; }
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"There are additional parsing words whose syntax is delimited by " { $link POSTPONE: ; } ", and they are all implemented by calling " { $link parse-definition } "." ;
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ARTICLE: "parsing-tokens" "Parsing raw tokens"
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"So far we have seen how to read individual tokens, or read a sequence of parsed objects until a delimiter. It is also possible to read raw tokens from the input and perform custom processing."
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$nl
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"One example is the " { $link POSTPONE: USING: } " parsing word."
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{ $see POSTPONE: USING: }
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"It reads a list of vocabularies terminated by " { $link POSTPONE: ; } ". However, the vocabulary names do not name words, except by coincidence; so " { $link parse-until } " cannot be used here. Instead, a lower-level word is called:"
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{ $subsection parse-tokens } ;
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ARTICLE: "parsing-words" "Parsing words"
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"The Factor parser is follows a simple recursive-descent design. The parser reads successive tokens from the input; if the token identifies a number or an ordinary word, it is added to an accumulator vector. Otherwise if the token identifies a parsing word, the parsing word is executed immediately."
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$nl
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"Parsing words are marked by suffixing the definition with a " { $link POSTPONE: parsing } " declaration. Here is the simplest possible parsing word; it prints a greeting at parse time:"
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{ $code ": hello \"Hello world\" print ; parsing" }
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"Parsing words must have stack effect " { $snippet "( accum -- accum )" } ", where " { $snippet "accum" } " is the accumulator vector supplied by the parser. Parsing words can read input, add word definitions to the dictionary, and do anything an ordinary word can."
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$nl
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"Tools for implementing parsing words:"
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{ $subsection "reading-ahead" }
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{ $subsection "parsing-word-nest" }
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{ $subsection "defining-words" }
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{ $subsection "parsing-tokens" } ;
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ARTICLE: "parser-lexer" "The lexer"
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"Two variables that encapsulate internal parser state:"
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{ $subsection file }
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{ $subsection lexer }
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"Creating a default lexer:"
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{ $subsection <lexer> }
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"A word to test of the end of input has been reached:"
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{ $subsection still-parsing? }
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"A word to get the text of the current line:"
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{ $subsection line-text }
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"A word to advance the lexer to the next line:"
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{ $subsection next-line }
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"Two generic words to override the lexer's token boundary detection:"
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{ $subsection skip-blank }
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{ $subsection skip-word }
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"A utility used when parsing string literals:"
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{ $subsection parse-string }
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"The parser can be invoked with a custom lexer:"
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{ $subsection (parse-lines) }
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{ $subsection with-parser } ;
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ARTICLE: "parser-files" "Parsing source files"
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"The parser can run source files:"
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{ $subsection run-file }
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{ $subsection parse-file }
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{ $subsection bootstrap-file }
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"The parser cross-references source files and definitions. This allows it to keep track of removed definitions, and prevent forward references and accidental redefinitions."
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$nl
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"When a source file is reloaded, the parser compares the previous list of definitions with the current list; any definitions which are no longer present in the file are removed by a call to " { $link forget } ". A warning message is printed if any other definitions still depend on the removed definitions."
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$nl
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"The parser also catches forward references when reloading source files. This is best illustrated with an example. Suppose we load a source file " { $snippet "a.factor" } ":"
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{ $code
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"USING: io sequences ;"
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"IN: a"
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": hello \"Hello\" ;"
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": world \"world\" ;"
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": hello-world hello " " world 3append print ;"
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}
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"The definitions for " { $snippet "hello" } ", " { $snippet "world" } ", and " { $snippet "hello-world" } " are in the dictionary."
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$nl
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"Now, after some heavily editing and refactoring, the file looks like this:"
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{ $code
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"USING: namespaces ;"
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"IN: a"
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": hello \"Hello\" % ;"
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": hello-world [ hello " " % world ] \"\" make ;"
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": world \"world\" % ;"
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}
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"Note that the developer has made a mistake, placing the definition of " { $snippet "world" } " " { $emphasis "after" } " its usage in " { $snippet "hello-world" } "."
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$nl
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"If the parser did not have special checks for this case, then the modified source file would still load, because when the definition of " { $snippet "hello-world" } " on line 4 is being parsed, the " { $snippet "world" } " word is already present in the dictionary from an earlier run. The developer would then not discover this mistake until attempting to load the source file into a fresh image."
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$nl
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"Since this is undesirable, the parser explicitly raises an error if a source file refers to a word which is in the dictionary, but defined after it is used."
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{ $subsection forward-error }
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"If a source file raises a " { $link forward-error } " when loaded into a development image, then it would have raised a " { $link no-word } " error when loaded into a fresh image."
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$nl
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"The parser also catches duplicate definitions. If an artifact is defined twice in the same source file, the earlier definition will never be accessible, and this is almost always a mistake, perhaps due to a bad choice of word names, or a copy and paste error. The parser raises an error in this case."
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{ $subsection redefine-error }
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{ $see-also "source-files" } ;
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ARTICLE: "parser-usage" "Reflective parser usage"
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"The parser can be called on a string:"
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{ $subsection eval }
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{ $subsection parse }
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{ $subsection parse-fresh }
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"The parser can also parse from a stream:"
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{ $subsection parse-stream } ;
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ARTICLE: "parser" "The parser"
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"This parser is a general facility for reading textual representations of objects and definitions. The parser is implemented in the " { $vocab-link "parser" } " and " { $vocab-link "syntax" } " vocabularies."
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$nl
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"This section concerns itself with usage and extension of the parser. Standard syntax is described in " { $link "syntax" } "."
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{ $subsection "vocabulary-search" }
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{ $subsection "parser-files" }
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{ $subsection "parser-usage" }
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"The parser can be extended."
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{ $subsection "parsing-words" }
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{ $subsection "parser-lexer" } ;
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ABOUT: "parser"
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: $parsing-note
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drop
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"This word should only be called from parsing words."
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$notes ;
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HELP: lexer
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{ $var-description "Stores the current " { $link lexer } " instance." }
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{ $class-description "An object for tokenizing parser input. It has the following slots:"
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{ $list
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{ { $link lexer-text } " - the lines being parsed; an array of strings" }
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{ { $link lexer-line } " - the line number being parsed; unlike most indices this is 1-based for friendlier error reporting and integration with text editors" }
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{ { $link lexer-column } " - the current column position, zero-based" }
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}
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"Custom lexing can be implemented by delegating a tuple to an instance of this class and implementing the " { $link skip-word } " and " { $link skip-blank } " generic words." } ;
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HELP: <lexer>
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{ $values { "text" "a sequence of strings" } { "lexer" lexer } }
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{ $description "Creates a new lexer for tokenizing the given sequence of lines." } ;
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HELP: location
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{ $values { "loc" "a " { $snippet "{ path line# }" } " pair" } }
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{ $description "Outputs the current parser location. This value can be passed to " { $link set-where } " or " { $link (save-location) } "." } ;
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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: redefinition?
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{ $values { "definition" "a definition specifier" } { "?" "a boolean" } }
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{ $description "Tests if this definition is already present in the current source file." }
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$parsing-note ;
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HELP: (save-location)
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{ $values { "definition" "a definition specifier" } { "loc" "a " { $snippet "{ path line# }" } " pair" } }
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{ $description "Saves the location of a definition and associates this definition with the current source file."
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$nl
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"This is the book-keeping required to detect " { $link redefine-error } " and " { $link forward-error } "." } ;
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HELP: save-location
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{ $values { "definition" "a definition specifier" } }
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{ $description "Saves the location of a definition and associates this definition with the current source file."
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$nl
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"This is the book-keeping required to detect " { $link redefine-error } " and " { $link forward-error } "." } ;
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HELP: parser-notes
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{ $var-description "A boolean controlling whether the parser will print various notes and warnings. Switched on by default. If a source file is being run for its effect on the " { $link stdio } " stream, this variable should be switched off, to prevent parser notes from polluting the output." } ;
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HELP: parser-notes?
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{ $values { "?" "a boolean" } }
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{ $description "Tests if the parser will print various notes and warnings. To disable parser notes, either set " { $link parser-notes } " to " { $link f } ", or pass the " { $snippet "-quiet" } " command line switch." } ;
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HELP: next-line
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{ $values { "lexer" lexer } }
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{ $description "Advances the lexer to the next input line, discarding the remainder of the current line." } ;
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HELP: file
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{ $var-description "Stores the " { $link source-file } " being parsed. The " { $link source-file-path } " of this object comes from the input parameter to " { $link parse-stream } "." } ;
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HELP: old-definitions
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{ $var-description "Stores an assoc where the keys 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 an assoc where the keys form the set of definitions which were defined so far by the current parsing of " { $link file } "." } ;
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HELP: parse-error
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{ $error-description "Thrown when the parser encounters invalid input. A parse error wraps an underlying error and holds the file being parsed, line number, and column number." } ;
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HELP: <parse-error>
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{ $values { "msg" "an error" } { "error" parse-error } }
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{ $description "Creates a new " { $link parse-error } ", filling in the location information from the current " { $link lexer } "." } ;
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HELP: line-text
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{ $values { "lexer" lexer } { "str" string } }
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{ $description "Outputs the text of the line being parsed." } ;
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HELP: skip
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{ $values { "i" "a starting index" } { "seq" "a sequence" } { "quot" "a quotation with stack effect " { $snippet "( elt -- ? )" } } { "n" integer } }
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{ $description "Variant of " { $link find* } " that outputs the length of the sequence instead of " { $link f } " if no elements satisfy the predicate." } ;
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HELP: change-column
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{ $values { "lexer" lexer } { "quot" "a quotation with stack effect " { $snippet "( col line -- newcol )" } } }
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{ $description "Applies a quotation to the current column and line text to produce a new column, and moves the lexer position." } ;
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HELP: skip-blank
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{ $values { "lexer" lexer } }
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{ $contract "Skips whitespace characters." }
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{ $notes "Custom lexers can implement this generic word." } ;
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HELP: skip-word
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{ $values { "lexer" lexer } }
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{ $contract
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"Skips until the end of the current token."
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$nl
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"The default implementation treats a single " { $snippet "\"" } " as a word by itself; otherwise it searches forward until a whitespace character or the end of the line."
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}
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{ $notes "Custom lexers can implement this generic word." } ;
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HELP: still-parsing-line?
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{ $values { "lexer" lexer } { "?" "a boolean" } }
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{ $description "Outputs " { $link f } " if the end of the current line has been reached, " { $link t } " otherwise." } ;
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HELP: parse-token
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{ $values { "lexer" lexer } { "str/f" "a " { $link string } " or " { $link f } } }
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{ $description "Reads the next token from the lexer. Tokens are delimited by whitespace, with the exception that " { $snippet "\"" } " is treated like a single token even when not followed by whitespace." } ;
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HELP: scan
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{ $values { "str/f" "a " { $link string } " or " { $link f } } }
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{ $description "Reads the next token from the lexer. See " { $link parse-token } " for details." }
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$parsing-note ;
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HELP: bad-escape
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{ $error-description "Indicates the parser encountered an invalid escape code following a backslash (" { $snippet "\\" } ") in a string literal. See " { $link "escape" } " for a list of valid escape codes." } ;
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HELP: bad-number
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{ $error-description "Indicates the parser encountered an invalid numeric literal." } ;
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HELP: escape
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{ $values { "escape" "a single-character escape" } { "ch" "a character" } }
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{ $description "Converts from a single-character escape code and the corresponding character." }
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{ $examples { $example "CHAR: n escape CHAR: \\n = ." "t" } } ;
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HELP: next-escape
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{ $values { "m" "an index into " { $snippet "str" } } { "str" string } { "n" "an index into " { $snippet "str" } } { "ch" "a character" } }
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{ $description "Helper word for " { $link parse-string } " which parses an escape sequence starting at the " { $snippet "m" } "th index of " { $snippet "str" } "." }
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{ $errors "Throws a " { $link bad-escape } " if the string contains an invalid escape sequence." } ;
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HELP: next-char
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{ $values { "m" "an index into " { $snippet "str" } } { "str" string } { "n" "an index into " { $snippet "str" } } { "ch" "a character" } }
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{ $description "Helper word for " { $link parse-string } " which parses a character starting at the " { $snippet "m" } "th index of " { $snippet "str" } "." } ;
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HELP: parse-string
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{ $values { "str" "a new " { $link string } } }
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{ $description "Parses the line until a quote (\"), interpreting escape codes along the way." }
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{ $errors "Throws an " { $link bad-escape } " if the string contains an invalid escape sequence." }
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$parsing-note ;
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HELP: still-parsing?
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{ $values { "lexer" lexer } { "?" "a boolean" } }
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{ $description "Outputs " { $link f } " if end of input has been reached, " { $link t } " otherwise." } ;
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HELP: use
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{ $var-description "A variable holding the current vocabulary search path as a sequence of assocs." } ;
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{ use in use+ (use+) set-use set-in POSTPONE: USING: POSTPONE: USE: file-vocabs } related-words
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HELP: in
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{ $var-description "A variable holding the name of the current vocabulary for new definitions." } ;
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HELP: shadow-warnings
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{ $values { "vocab" "an assoc mapping strings to words" } { "vocabs" "a sequence of assocs" } }
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{ $description "Tests if any keys in " { $snippet "vocab" } " shadow keys in the elements of " { $snippet "vocabs" } ", and if so, prints a warning message. These warning messages can be disabled by setting " { $link parser-notes } " to " { $link f } "." } ;
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HELP: (use+)
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{ $values { "vocab" "an assoc mapping strings to words" } }
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{ $description "Adds an assoc at the front of the search path." }
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$parsing-note ;
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HELP: use+
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{ $values { "vocab" string } }
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{ $description "Adds a new vocabulary at the front of the search path after loading it if necessary. Subsequent word lookups by the parser will search this vocabulary first." }
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$parsing-note
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{ $errors "Throws an error if the vocabulary does not exist." } ;
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HELP: set-use
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{ $values { "seq" "a sequence of strings" } }
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{ $description "Sets the vocabulary search path. Later vocabularies take precedence." }
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{ $errors "Throws an error if one of the vocabularies does not exist." }
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$parsing-note ;
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HELP: add-use
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{ $values { "seq" "a sequence of strings" } }
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{ $description "Adds multiple vocabularies to the search path, with later vocabularies taking precedence." }
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{ $errors "Throws an error if one of the vocabularies does not exist." }
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$parsing-note ;
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HELP: set-in
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{ $values { "name" string } }
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{ $description "Sets the current vocabulary where new words will be defined, creating the vocabulary first if it does not exist." }
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$parsing-note ;
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HELP: create-in
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{ $values { "string" "a word name" } { "word" "a new word" } }
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{ $description "Creates a word in the current vocabulary. Until re-defined, the word throws an error when invoked." }
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$parsing-note ;
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HELP: parse-tokens
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{ $values { "end" string } { "seq" "a new sequence of strings" } }
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{ $description "Reads a sequence of tokens until the first occurrence of " { $snippet "end" } ". The tokens remain as strings and are not processed in any way." }
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{ $examples "This word is used to implement " { $link POSTPONE: USING: } "." }
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$parsing-note ;
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HELP: CREATE
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{ $values { "word" word } }
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{ $description "Reads the next token from the line currently being parsed, and creates a word with that name in the current vocabulary." }
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{ $errors "Throws an error if the end of the line is reached." }
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$parsing-note ;
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HELP: no-word
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{ $values { "name" string } { "newword" word } }
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{ $description "Throws a " { $link no-word } " error." }
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{ $error-description "Thrown if the parser encounters a token which does not name a word in the current vocabulary search path. If any words with this name exist in vocabularies not part of the search path, a number of restarts will offer to add those vocabularies to the search path and use the chosen word." }
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{ $notes "Apart from a missing " { $link POSTPONE: USE: } ", this error can also indicate an ordering issue. In Factor, words must be defined before they can be called. Mutual recursion can be implemented via " { $link POSTPONE: DEFER: } "." } ;
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HELP: search
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{ $values { "str" string } { "word" word } }
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{ $description "Searches for a word by name in the current vocabulary search path. If no such word could be found, throws a " { $link no-word } " error. If the search path does not contain a word with this name but other vocabularies do, the error will have restarts offering to add vocabularies to the search path." }
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$parsing-note ;
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HELP: forward-error
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{ $values { "word" word } }
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{ $description "Throws a " { $link forward-error } "." }
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{ $description "Indicates a word is being referenced prior to the location of its most recent definition. This can only happen if a source file is loaded, and subsequently edited such that two dependent definitions are reversed." } ;
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HELP: scan-word
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{ $values { "word/number/f" "a word, number or " { $link f } } }
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{ $description "Reads the next token from parser input. If the token is a valid number literal, it is converted to a number, otherwise the dictionary is searched for a word named by the token. Outputs " { $link f } " if the end of the input has been reached." }
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{ $errors "Throws an error if the token does not name a word, and does not parse as a number." }
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$parsing-note ;
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HELP: unexpected
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{ $values { "want" "a " { $link word } " or " { $link f } } { "got" word } }
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{ $description "Throws an " { $link unexpected } " error." }
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{ $error-description "Thrown by the parser if an unmatched closing delimiter is encountered." }
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{ $examples
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"Parsing the following snippet will throw this error:"
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{ $code "[ 1 2 3 }" }
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} ;
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HELP: unexpected-eof
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{ $values { "word" "a " { $link word } } }
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{ $description "Throws an " { $link unexpected } " error indicating the parser was looking for an occurrence of " { $snippet "word" } " but encountered end of file." } ;
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HELP: parse-step
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{ $values { "accum" vector } { "end" word } { "?" "a boolean" } }
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{ $description "Parses a token. If the token is a number or an ordinary word, it is added to the accumulator. If it is a parsing word, calls the parsing word with the accumulator on the stack. Outputs " { $link f } " if " { $snippet "end" } " is encountered, " { $link t } " otherwise." }
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$parsing-note ;
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HELP: (parse-until)
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{ $values { "accum" vector } { "end" word } }
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{ $description "Parses objects from parser input until " { $snippet "end" } " is encountered, adding them to the accumulator." }
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$parsing-note ;
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HELP: parse-until
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{ $values { "end" word } { "vec" "a new vector" } }
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{ $description "Parses objects from parser input until " { $snippet "end" } ". Outputs a new vector with the results." }
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{ $examples "This word is used to implement " { $link POSTPONE: ARTICLE: } "." }
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$parsing-note ;
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{ parse-tokens (parse-until) parse-until } related-words
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HELP: parsed
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{ $values { "accum" vector } { "obj" object } }
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{ $description "Convenience word for parsing words. It behaves exactly the same as " { $link push } ", except the accumulator remains on the stack." }
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$parsing-note ;
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HELP: with-parser
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{ $values { "lexer" lexer } { "quot" "a quotation with stack effect " { $snippet "( -- accum )" } } { "newquot" "a new " { $link quotation } } }
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{ $description "Sets up the parser and calls the quotation. The quotation can make use of parsing words such as " { $link scan } " and " { $link parse-until } ". It must yield a sequence, which is converted to a quotation and output. Any errors thrown by the quotation are wrapped in parse errors." } ;
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HELP: (parse-lines)
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{ $values { "lexer" lexer } { "quot" "a new " { $link quotation } } }
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{ $description "Parses Factor source code using a custom lexer. The vocabulary search path is taken from the current scope." }
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{ $errors "Throws a " { $link parse-error } " if the input is malformed." } ;
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HELP: parse-lines
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{ $values { "lines" "a sequence of strings" } { "quot" "a new " { $link quotation } } }
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{ $description "Parses Factor source code which has been tokenized into lines. The vocabulary search path is taken from the current scope." }
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{ $errors "Throws a " { $link parse-error } " if the input is malformed." } ;
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HELP: lexer-factory
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{ $var-description "A variable holding a quotation with stack effect " { $snippet "( lines -- lexer )" } ". This quotation is called by the parser to create " { $link lexer } " instances. This variable can be rebound to a quotation which outputs a custom tuple delegating to " { $link lexer } " to customize syntax." } ;
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HELP: parse-effect
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{ $values { "effect" "an instance of " { $link effect } } }
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{ $description "Parses a stack effect from the current input line." }
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{ $examples "This word is used by " { $link POSTPONE: ( } " to parse stack effect declarations." }
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$parsing-note ;
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HELP: parse-base
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{ $values { "base" "an integer between 2 and 36" } { "parsed" integer } }
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{ $description "Reads an integer in a specific numerical base from the parser input." }
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$parsing-note ;
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HELP: parse-literal
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{ $values { "accum" vector } { "end" word } { "quot" "a quotation with stack effect " { $snippet "( seq -- obj )" } } }
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{ $description "Parses objects from parser input until " { $snippet "end" } ", applies the quotation to the resulting sequence, and adds the output value to the accumulator." }
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{ $examples "This word is used to implement " { $link POSTPONE: C{ } "." }
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$parsing-note ;
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HELP: parse-definition
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|
{ $values { "quot" "a new " { $link quotation } } }
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{ $description "Parses objects from parser input until " { $link POSTPONE: ; } " and outputs a quotation with the results." }
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{ $examples "This word is used to implement " { $link POSTPONE: : } "." }
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$parsing-note ;
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HELP: bootstrap-syntax
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{ $var-description "Only set during bootstrap. Stores a copy of the " { $link vocab-words } " of the host's syntax vocabulary; this allows the host's parsing words to be used during bootstrap source parsing, not the target's." } ;
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HELP: file-vocabs
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|
{ $description "Installs the initial the vocabulary search path for parsing a file. This consists of the " { $snippet "syntax" } " vocabulary together with the " { $snippet "scratchpad" } " vocabulary." } ;
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HELP: parse
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{ $values { "str" string } { "quot" quotation } }
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{ $description "Parses Factor source code from a string. The current vocabulary search path is used." }
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{ $errors "Throws a parse error if the input is malformed." } ;
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HELP: parse-fresh
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{ $values { "lines" "a sequence of strings" } { "quot" quotation } }
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{ $description "Parses Factor source code in a sequence of lines. The initial vocabulary search path is used (see " { $link file-vocabs } ")." }
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{ $errors "Throws a parse error if the input is malformed." } ;
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HELP: eval
|
|
{ $values { "str" string } }
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{ $description "Parses Factor source code from a string, and calls the resulting quotation. The current vocabulary search path is used." }
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{ $errors "Throws an error if the input is malformed, or if the quotation throws an error." } ;
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HELP: parse-hook
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{ $var-description "A quotation called by " { $link parse-stream } " after parsing the input stream. The default value recompiles new word definitions; see " { $link "recompile" } " for details." } ;
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{ parse-hook no-parse-hook } related-words
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HELP: no-parse-hook
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{ $values { "quot" "a quotation" } }
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{ $description "Runs the quotation in a new dynamic scope where " { $link parse-hook } " is set to " { $link f } ", then calls the outer " { $link parse-hook } " after the quotation returns. This has the effect of postponing any recompilation to the end of a quotation." } ;
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HELP: start-parsing
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|
{ $values { "stream" "an input stream" } { "name" "a pathname string" } }
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|
{ $description "Prepares to parse a source file by reading the entire contents of the stream and setting some variables. The pathname identifies the stream for cross-referencing purposes." }
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|
{ $errors "Throws an I/O error if there was an error reading from the stream." }
|
|
{ $notes "This is one of the factors of " { $link parse-stream } "." } ;
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HELP: outside-usages
|
|
{ $values { "seq" "a sequence of definitions" } { "usages" "an association list mapping definitions to sequences of definitions" } }
|
|
{ $description "Outputs an association list mapping elements of " { $snippet "seq" } " to lists of usages which exclude the definitions in " { $snippet "seq" } " themselves." } ;
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|
HELP: filter-moved
|
|
{ $values { "assoc" "an assoc where the keys are definitions" } { "newassoc" "an assoc where the keys are definitions" } }
|
|
{ $description "Removes all definitions from the assoc which are no longer present in the current " { $link file } "." } ;
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|
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HELP: smudged-usage
|
|
{ $values { "usages" "a sequence of definitions which reference removed definitions" } { "referenced" "a sequence of definitions removed from this source file which are still referenced elsewhere" } { "removed" "a sequence of definitions removed from this source file" } }
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|
{ $description "Collects information about changed word definitioins after parsing." } ;
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|
HELP: forget-smudged
|
|
{ $description "Forgets removed definitions and prints a warning message if any of them are still referenced from other source files." } ;
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|
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|
HELP: record-definitions
|
|
{ $values { "file" source-file } }
|
|
{ $description "Records that all " { $link new-definitions } " were defined in " { $snippet "file" } "." } ;
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|
HELP: finish-parsing
|
|
{ $values { "quot" "the quotation just parsed" } }
|
|
{ $description "Records information to the current " { $link file } " and prints warnings about any removed definitions which are still in use." }
|
|
{ $notes "This is one of the factors of " { $link parse-stream } "." } ;
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|
|
|
HELP: undo-parsing
|
|
{ $description "Records information to the current " { $link file } " after an incomplete parse which ended with an error." } ;
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|
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|
HELP: parse-stream
|
|
{ $values { "stream" "an input stream" } { "name" "a file name for error reporting and cross-referencing" } { "quot" quotation } }
|
|
{ $description "Parses Factor source code read from the stream. The initial vocabulary search path is used." }
|
|
{ $errors "Throws an I/O error if there was an error reading from the stream. Throws a parse error if the input is malformed." } ;
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HELP: parse-file
|
|
{ $values { "file" "a pathname string" } { "quot" quotation } }
|
|
{ $description "Parses the Factor source code stored in a file. The initial vocabulary search path is used." }
|
|
{ $errors "Throws an I/O error if there was an error reading from the file. Throws a parse error if the input is malformed." } ;
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|
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|
HELP: run-file
|
|
{ $values { "file" "a pathname string" } }
|
|
{ $description "Parses the Factor source code stored in a file and runs it. The initial vocabulary search path is used." }
|
|
{ $errors "Throws an error if loading the file fails, there input is malformed, or if a runtime error occurs while calling the parsed quotation." } ;
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|
|
HELP: ?run-file
|
|
{ $values { "path" "a pathname string" } }
|
|
{ $description "If the file exists, runs it with " { $link run-file } ", otherwise does nothing." } ;
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|
|
|
HELP: reload
|
|
{ $values { "defspec" "a definition specifier" } }
|
|
{ $description "Reloads the source file containing the definition." }
|
|
{ $examples
|
|
"Reloading a word definition:"
|
|
{ $code "\\ foo reload" }
|
|
"A word's documentation:"
|
|
{ $code "\\ foo >link reload" }
|
|
"A method definition:"
|
|
{ $code "{ editor draw-gadget* } reload" }
|
|
"A help article:"
|
|
{ $code "\"handbook\" >link reload" }
|
|
} ;
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|
|
|
HELP: bootstrap-file
|
|
{ $values { "path" "a pathname string" } }
|
|
{ $description "If bootstrapping, parses the source file and adds its top level form to the quotation being constructed with " { $link make } "; the bootstrap code uses this to build up a boot quotation to be run on image startup. If not bootstrapping, just runs the file normally." } ;
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|
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|
HELP: ?bootstrap-file
|
|
{ $values { "path" "a pathname string" } }
|
|
{ $description "If the file exists, loads it with " { $link bootstrap-file } ", otherwise does nothing." } ;
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|
|
|
HELP: eval>string
|
|
{ $values { "str" string } { "output" string } }
|
|
{ $description "Evaluates the Factor code in " { $snippet "str" } " with the " { $link stdio } " stream rebound to a string output stream, then outputs the resulting string." } ;
|