▼ |  | Dr Racket Plugins

1 | Implementing Dr Racket Plugins
2 | Adding Languages to Dr Racket
3 | Creating New Kinds of Dr Racket Frames
4 | Extending the Existing Dr Racket Classes
5 | Expanding the User’s Program Text and Breaking
6 | Editor Modes
7 | Language-Specific Capabilities
8 | Check Syntax
9 | Teaching Languages
10 | Signatures
11 | drracket: get/ extend
12 | drracket: unit
13 | drracket: language
14 | drracket: language-configuration
15 | drracket: debug
16 | drracket: rep
17 | drracket: frame
18 | drracket: help-desk
19 | drracket: eval
20 | drracket: modes
21 | drracket: module-language-tools
22 | drracket: module-language
23 | Backwards Compatibility
| Index

► | 8 | Check Syntax

8.1 | Accessing Check Syntax Programmatically
8.2 | Check Syntax Button
8.3 | Syntax Properties that Check Syntax Looks For

On this page:

8.1`` Accessing Check Syntax Programmatically
make-traversal
current-annotations
current-max-to-send-at-once
syncheck-annotations<%>
syncheck: find-source-object
syncheck: add-background-color
syncheck: add-require-open-menu
syncheck: add-docs-menu
syncheck: add-id-set
syncheck: add-arrow
syncheck: add-arrow/ name-dup
syncheck: add-tail-arrow
syncheck: add-mouse-over-status
syncheck: add-jump-to-definition
syncheck: add-definition-target
syncheck: color-range
syncheck: add-rename-menu
annotations-mixin
syncheck: find-source-object
syncheck: add-background-color
syncheck: add-require-open-menu
syncheck: add-docs-menu
syncheck: add-rename-menu
syncheck: add-arrow
syncheck: add-arrow/ name-dup
syncheck: add-tail-arrow
syncheck: add-mouse-over-status
syncheck: add-jump-to-definition
syncheck: add-id-set
syncheck: color-range
8.2`` Check Syntax Button
syncheck-drracket-button
syncheck: button-callback
syncheck-bitmap
8.3`` Syntax Properties that Check Syntax Looks For

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### 8`` Check Syntax

Check Syntax is a part of the DrRacket collection, but is implemented via the tools API.

#### 8.1`` Accessing Check Syntax Programmatically

(require drracket/check-syntax) | package: drracket

> > procedure
> > (make-traversal namespace path) |  | → |  |
> > (->* (syntax?)
> > ((-> any/c void?))
> > void?)
> > (-> void?)
> namespace : namespace?
> path : (or/c #f path-string?)

This function creates some local state about a traversal of syntax objects and returns two functions. The first one should be called with each of the (fully expanded) syntax objects that make up a program (there will be only one if the program is a module) and then the second one should be called to indicate there are no more.

The optional argument to the first function is ignored. It is left there for historical reasons. In the past it was called for each sequence of binding identifiers encountered in define-values, define-syntaxes, and define-values-for-syntax.

During the dynamic extent of the call to the two result functions, the value of the current-annotations parameter is consulted and various methods are invoked in the corresponding object (if any), to indicate what has been found in the syntax object. These methods will only be called if the syntax objects have source locations.

> parameter (current-annotations)
> → (or/c #f (is-a?/c syncheck-annotations<%>))
> (current-annotations ca) → void?
> ca : (or/c #f (is-a?/c syncheck-annotations<%>))

The methods of the value of this parameter are invoked by the functions returned from make-traversal.

> parameter (current-max-to-send-at-once)
> → (or/c +inf.0 (and/c exact-integer? (>=/c 2)))
> (current-max-to-send-at-once m) → void?
> m : (or/c +inf.0 (and/c exact-integer? (>=/c 2)))

No longer used.

interface syncheck-annotations<%> : interface?

Classes implementing this interface are accceptors of information about a traversal of syntax objects. See make-traversal.
Do not implement this interface directly, as it is liable to change without warning. Instead, use the annotations-mixin and override the methods you’re interested in. The annotations-mixin will keep in sync with this interface, providing methods that ignore their arguments.

> > method (send a-syncheck-annotations syncheck:find-source-object stx)
> > → (or/c #f (not/c #f))
> > stx : syntax?

> This should return #f if the source of this syntax object is uninteresting for annotations (if, for example, the only interesting annotations are those in the original file and this is a syntax object introduced by a macro and thus has a source location from some other file).

> Otherwise, it should return some (non-#f) value that will then be passed to one of the other methods below as a source-obj argument.

> > > method
> > > (send a-syncheck-annotations syncheck:add-background-color |
> > > |  | source-obj |
> > > |  | start |
> > > |  | end |
> > > |  | color) |
> > → void?
> > source-obj : (not/c #f)
> > start : exact-nonnegative-integer?
> > end : exact-nonnegative-integer?
> > color : string?

> Called to indicate that the color color should be drawn on the background of the given range in the editor, when the mouse moves over it. This method is typically called in conjuction with some other method that provides some other annotation on the source.

> > > method
> > > (send a-syncheck-annotations syncheck:add-require-open-menu |
> > > |  | source-obj |
> > > |  | start |
> > > |  | end |
> > > |  | file) |
> > → void?
> > source-obj : (not/c #f)
> > start : exact-nonnegative-integer?
> > end : exact-nonnegative-integer?
> > file : path-string?

> Called to indicate that there is a require at the location from start to end, and that it corresponds to file. Check Syntax adds a popup menu.

> > > method
> > > (send a-syncheck-annotations syncheck:add-docs-menu |
> > > |  | source-obj |
> > > |  | start |
> > > |  | end |
> > > |  | id |
> > > |  | label |
> > > |  | path |
> > > |  | tag) |
> > → void?
> > source-obj : (not/c #f)
> > start : exact-nonnegative-integer?
> > end : exact-nonnegative-integer?
> > id : symbol?
> > label : any/c
> > path : any/c
> > tag : any/c

> Called to indicate that there is something that has documentation between the range start and end. The documented identifier’s name is given by id and the docs are found in the html file path at the html tag tag. The label argument describes the binding for use in the menu item (although it may be longer than 200 characters).

> > > method
> > > (send a-syncheck-annotations syncheck:add-id-set |
> > > |  | all-ids |
> > > |  | new-name-interferes?) |
> > → void?
> > | all-ids |  | : |  |
> > (listof (list/c (not/c #f)
> > exact-nonnegative-integer?
> > exact-nonnegative-integer?))
> > new-name-interferes? : (-> symbol boolean?)

> This method is no longer called by Check Syntax. It is here for backwards compatibility only. The information it provided must now be synthesized from the information supplied to syncheck:add-arrow/name-dup.

> > > method
> > > (send a-syncheck-annotations syncheck:add-arrow |
> > > |  | start-source-obj |
> > > |  | start-left |
> > > |  | start-right |
> > > |  | end-source-obj |
> > > |  | end-left |
> > > |  | end-right |
> > > |  | actual? |
> > > |  | phase-level) |
> > → void?
> > start-source-obj : (not/c #f)
> > start-left : exact-nonnegative-integer?
> > start-right : exact-nonnegative-integer?
> > end-source-obj : (not/c #f)
> > end-left : exact-nonnegative-integer?
> > end-right : exact-nonnegative-integer?
> > actual? : boolean?
> > phase-level : (or/c exact-nonnegative-integer? #f)

> This function is not called directly anymore by Check Syntax. Instead syncheck:add-arrow/name-dup is.

> This method is invoked by the default implementation of syncheck:add-arrow/name-dup in annotations-mixin.

> > > method
> > > (send a-syncheck-annotations syncheck:add-arrow/name-dup |
> > > |  | start-source-obj |
> > > |  | start-left |
> > > |  | start-right |
> > > |  | end-source-obj |
> > > |  | end-left |
> > > |  | end-right |
> > > |  | actual? |
> > > |  | phase-level |
> > > |  | require-arrow? |
> > > |  | name-dup?) |
> > → void?
> > start-source-obj : (not/c #f)
> > start-left : exact-nonnegative-integer?
> > start-right : exact-nonnegative-integer?
> > end-source-obj : (not/c #f)
> > end-left : exact-nonnegative-integer?
> > end-right : exact-nonnegative-integer?
> > actual? : boolean?
> > phase-level : (or/c exact-nonnegative-integer? #f)
> > require-arrow? : boolean?
> > name-dup? : (-> string? boolean?)

> Called to indicate that there should be an arrow between the locations described by the first six arguments.

> The phase-level argument indicates the phase of the binding and the actual? argument indicates if the binding is a real one, or a predicted one from a syntax template (predicted bindings are drawn with question marks in Check Syntax).

> The require-arrow? argument indicates if this arrow points from an imported identifier to its corresponding require.

> The name-dup? predicate returns #t in case that this variable (either the start or end), when replaced with the given string, would shadow some other binding (or otherwise interfere with the binding structure of the program at the time the program was expanded).

> > > method
> > > (send a-syncheck-annotations syncheck:add-tail-arrow |
> > > |  | from-source-obj |
> > > |  | from-pos |
> > > |  | to-source-obj |
> > > |  | to-pos) |
> > → void?
> > from-source-obj : (not/c #f)
> > from-pos : exact-nonnegative-integer?
> > to-source-obj : (not/c #f)
> > to-pos : exact-nonnegative-integer?

> Called to indicate that there are two expressions, beginning at from-pos and to-pos that are in tail position with respect to each other.

> > > method
> > > (send a-syncheck-annotations syncheck:add-mouse-over-status |
> > > |  | source-obj |
> > > |  | pos-left |
> > > |  | pos-right |
> > > |  | str) |
> > → void?
> > source-obj : (not/c #f)
> > pos-left : exact-nonnegative-integer?
> > pos-right : exact-nonnegative-integer?
> > str : string?

> Called to indicate that the message in str should be shown when the mouse passes over the given position.

> > > method
> > > (send a-syncheck-annotations syncheck:add-jump-to-definition |
> > > |  | source-obj |
> > > |  | start |
> > > |  | end |
> > > |  | id |
> > > |  | filename |
> > > |  | submods) |
> > → void?
> > source-obj : (not/c #f)
> > start : exact-nonnegative-integer?
> > end : exact-nonnegative-integer?
> > id : any/c
> > filename : path-string?
> > submods : (listof symbol?)

> Called to indicate that there is some identifier at the given location (named id) that is defined in the submods of the file filename (where an empty list in submods means that the identifier is defined at the top-level module).

> > > method
> > > (send a-syncheck-annotations syncheck:add-definition-target |
> > > |  | source-obj |
> > > |  | start |
> > > |  | finish |
> > > |  | style-name) |
> > → void?
> > source-obj : (not/c #f)
> > start : exact-nonnegative-integer?
> > finish : exact-nonnegative-integer?
> > style-name : any/c

> > > method
> > > (send a-syncheck-annotations syncheck:color-range |  | source-obj |
> > > |  | start |
> > > |  | finish |
> > > |  | style-name |
> > > |  | mode) |
> > → void?
> > source-obj : (not/c #f)
> > start : exact-nonnegative-integer?
> > finish : exact-nonnegative-integer?
> > style-name : any/c
> > mode : any/c

> Called to indicate that the given location should be colored according to the style style-name when in mode. The mode either indicates regular check syntax or is used indicate blame for potential contract violations (and still experimental).

> > > method
> > > (send a-syncheck-annotations syncheck:add-rename-menu |
> > > |  | id |
> > > |  | all-ids |
> > > |  | new-name-interferes?) |
> > → void?
> > id : symbol?
> > | all-ids |  | : |  |
> > (listof (list/c (not/c #f)
> > exact-nonnegative-integer?
> > exact-nonnegative-integer?))
> > new-name-interferes? : (-> symbol boolean?)

> This method is listed only for backwards compatibility. It is not called by Check Syntax anymore.

mixin annotations-mixin : (class? . -> . class?)
result implements: | syncheck-annotations<%>

Supplies all of the methods in syncheck-annotations<%> with default behavior. Be sure to use this mixin to future-proof your code and then override the methods you’re interested in.

By default:

- The syncheck:find-source-object method ignores its arguments and returns #f;

- the syncheck:add-arrow/name-dup method drops the require-arrow? and name-dup? arguments and calls syncheck:add-arrow; and

- all of the other methods ignore their arguments and return (void).

Here is an example showing how use this library to extract all of the arrows that Check Syntax would draw from various expressions. One subtle point: arrows are only included when the corresponding identifiers are syntax-original?; the code below manages this by copying the properties from an identifier that is syntax-original? in the call to datum->syntax.

> > (require drracket/check-syntax racket/class)
> > (define arrows-collector%
> (class (annotations-mixin object%)
> (super-new)
> (define/override (syncheck:find-source-object stx)
> stx)
> (define/override (syncheck:add-arrow/name-dup
> start-source-obj start-left start-right
> end-source-obj end-left end-right
> actual? phase-level require-arrow? name-dup?)
> (set! arrows
> (cons (list start-source-obj end-source-obj)
> arrows)))
> (define arrows '())
> (define/public (get-collected-arrows) arrows)))
> > (define (arrows form)
> (define base-namespace (make-base-namespace))
> (define-values (add-syntax done)
> (make-traversal base-namespace #f))
> (define collector (new arrows-collector%))
> (parameterize ([current-annotations collector]
> [current-namespace base-namespace])
> (add-syntax (expand form))
> (done))
> (send collector get-collected-arrows))
> > (define (make-id name pos orig?)
> (datum->syntax
> #f
> name
> (list #f #f #f pos (string-length (symbol->string name)))
> (and orig? #'is-orig)))
> > (arrows `(λ (,(make-id 'x 1 #t)) ,(make-id 'x 2 #t)))
> '((#<syntax::1 x> #<syntax::2 x>))
> > (arrows `(λ (x) x))
> '()
> > (arrows `(λ (,(make-id 'x 1 #f)) ,(make-id 'x 2 #t)))
> '()
> > (arrows `(λ (,(make-id 'x 1 #t)) x))
> '()

> syntax syncheck:find-source-object

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-background-color

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-require-open-menu

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-docs-menu

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-rename-menu

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-arrow

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-arrow/name-dup

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-tail-arrow

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-mouse-over-status

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-jump-to-definition

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:add-id-set

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

> syntax syncheck:color-range

Bound to an identifier created with define-local-member-name that is used in syncheck-annotations<%>.

#### 8.2`` Check Syntax Button

(require drracket/syncheck-drracket-button)
| package: drracket

> > value
> > syncheck-drracket-button | : |
> > (list/c
> > string?
> > (is-a?/c bitmap%)
> > (-> (is-a?/c
> > top-level-window<%>)
> > any))

This is meant to be used with the 'drracket:toolbar-buttons argument to the info proc returned from read-language.

> syntax syncheck:button-callback

This is defined with define-local-member-name and is bound to a method of no arguments of the DrRacket frame that runs Check Syntax.

> value syncheck-bitmap : (is-a?/c bitmap%)

The bitmap in the Check Syntax button on the DrRacket frame.

#### 8.3`` Syntax Properties that Check Syntax Looks For

Check Syntax collects the values of the syntax-propertys named 'disappeared-use, 'disappeared-binding, and 'sub-range-binders, and uses them to add additional arrows to the program text. These properties are intended for use when a macro discards or manufactures identifiers that, from the programmers perspective, should be binding each other.

For example, here is a macro that discards its arguments, but adds properties to the result syntax object so the arguments are treated as a binding/bound pair by Check Syntax.

> (define-syntax (m stx)
> (syntax-case stx ()
> [(_ id1 id2)
> (and (identifier? #'id1) (identifier? #'id2))
> (syntax-property
> (syntax-property
> #'1
> 'disappeared-use (list (syntax-local-introduce #'id1)))
> 'disappeared-binding (list (syntax-local-introduce #'id2)))]))

See also current-recorded-disappeared-uses.

The value of the 'sub-range-binders property is expected to be a tree of cons pairs (in any configuration) whose leaves are either ignored or are vectors of the shape

> (vector/c syntax? exact-nonnegative-integer? exact-nonnegative-integer?
> syntax? exact-nonnegative-integer? exact-nonnegative-integer?)

. If the leaf is a vector, the first syntax object is expected to be an identifier whose bound occurrences should have arrows that point to the syntax object in the fourth position in the vector. The numbers indicate the starting point and the range inside the corresponding identifier to consider as the location of the end of the arrow. Here’s an example:

> #lang racket/base
> (require (for-syntax racket/base))
> (define-syntax (define/hyphen stx)
> (syntax-case stx ()
> [(_ id1 id2 rhs-expr)
> (let ()
> (define first-part (symbol->string (syntax-e #'id1)))
> (define second-part (symbol->string (syntax-e #'id2)))
> (define first-len (string-length first-part))
> (define second-len (string-length second-part))
> (define hyphenated-id
> (datum->syntax
> #'id1
> (string->symbol (string-append first-part "-" second-part))))
> (syntax-property
> #`(define #,hyphenated-id rhs-expr)
> 'sub-range-binders
> (list
> (vector (syntax-local-introduce hyphenated-id)
> 0 first-len
> (syntax-local-introduce #'id1)
> 0 first-len)
> (vector (syntax-local-introduce hyphenated-id)
> (+ first-len 1) second-len
> (syntax-local-introduce #'id2)
> 0 second-len))))]))
> (define/hyphen big generator
> 11)
> (+ big-generator big-generator)

After putting this code in the DrRacket window, mouse over the words “big” and “generator” to see arrows pointing to the individual pieces of the identifier big-generator.

Finally, Check Syntax only draws arrows between identifiers that are syntax-original? or that have the syntax-property 'original-for-check-syntax set to #t.

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