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傳遞至規則或切面實作函式的結構定義物件。這個程式庫可存取分析目前目標所需的資訊和方法。

特別是,它可讓實作函式存取目前目標的標籤、屬性、設定和其依附元件的提供者。其中包含宣告輸出檔案的方法和產生這些檔案的動作。

情境物件在呼叫實作函式的期間基本上有效。在關聯函式以外的地方存取這些物件並不實用。詳情請參閱「規則」頁面

成員

作業

actions ctx.actions

包含宣告輸出檔案和產生這些檔案的方法。

aspect_ids

list ctx.aspect_ids

列出套用至目標的所有層面的 ID 清單。僅適用於切面實作函式。

Attr

struct ctx.attr

用來存取屬性值的結構體。屬性值是由使用者提供 (如果不是,則會採用預設值)。結構的屬性和值類型會對應至提供給 rule 函式attrs 字典的鍵和值。查看使用範例

bin_dir

root ctx.bin_dir

繫結目錄的根目錄。

build_file_path

string ctx.build_file_path

這項規則的 BUILD 檔案路徑 (相對於來源根目錄)。

build_setting_value

unknown ctx.build_setting_value

目前目標代表建構設定的值。如果這並非設定 build_setting 屬性規則的例項,則系統會顯示錯誤訊息。

設定

configuration ctx.configuration

預設設定。詳情請參閱設定類型。

coverage_instrumented

bool ctx.coverage_instrumented(target=None)

傳回是否要在為這項規則執行編譯動作時產生程式碼涵蓋率檢測,如果提供 target,則傳回該目標指定的規則。(如果提供了非規則或 Starlark 規則目標,則會傳回 False。)檢查目前規則的來源 (若未提供目標) 或目標來源是否應根據 --instrumentation_filter 和 --instrument_test_targets 配置設定進行檢測。這與設定中的 coverage_enabled 不同,後者會注意整個執行作業是否已啟用涵蓋率資料收集功能,但不會對特定目標進行檢測。

參數

參數 說明
target TargetNone;預設值為 None
:指定目標為規則的目標。如未提供,則會預設為目前的規則。

created_actions

StarlarkValue ctx.created_actions()

如果規則的 _skylark_testable 設為 True,則會傳回 Actions 供應器,代表目前已根據目前規則建立的所有動作。針對所有其他規則,則傳回 None。請注意,後續動作建立時不會更新供應器,因此如要檢查,您必須再次呼叫這個函式。

這是為了協助編寫規則實作輔助函式的測試,測試會接收 ctx 物件並建立動作。

disabled_features

list ctx.disabled_features

使用者針對這項規則明確停用的一組功能。

exec_groups

ExecGroupCollection ctx.exec_groups

這項規則可用的一組執行群組,按名稱建立索引。使用 ctx.exec_groups[name_of_group] 存取。

執行檔

struct ctx.executable

struct,包含以標籤類型屬性定義且標示為 executable=True 的可執行檔。struct 欄位對應的是屬性名稱。結構中的每個值都是 FileNone。如果規則中未指定選用屬性,則對應的結構值會是 None。如果標籤類型未標示為 executable=True,則不會產生相對應的結構體欄位。查看使用範例

expand_location

string ctx.expand_location(input, targets=[])

$(location //x) 替換為目標 //x 的輸出檔案路徑,展開指定字串中的所有 $(location ...) 範本。擴充功能僅適用於指向這項規則的直接依附性標籤,或是明確列於選用引數 targets 中的標籤。

$(location ...) 如果參照的目標有多項輸出內容,就會發生錯誤。在這種情況下,請使用 $(locations ...),因為這會產生以空格分隔的輸出路徑清單。這也可以安全地用於單一輸出檔案。

使用者可以使用此函式在 BUILD 檔案中指定指令 (例如 genrule)。在其他情況下,建議您直接控管標籤。

參數

參數 說明
input 要展開的字串。
要展開的字串。
targets 序列為「目標」;預設為 []
目標清單可提供額外查詢資訊。
可能會傳回 None

expand_make_variables

string ctx.expand_make_variables(attribute_name, command, additional_substitutions)

已淘汰。請改用 ctx.var 存取變數。
在展開所有「Make 變數」參照後傳回字串。變數必須採用下列格式:$(VAR_NAME)。其他班次:$$VAR_NAME expands to $VAR_NAME. Examples:
ctx.expand_make_variables("cmd", "$(MY_VAR)", {"MY_VAR": "Hi"})  # == "Hi"
ctx.expand_make_variables("cmd", "$$PWD", {})  # == "$PWD"
Additional variables may come from other places, such as configurations. Note that this function is experimental.

          
      

Parameters

Parameter Description
attribute_name required
The attribute name. Used for error reporting.
command required
The expression to expand. It can contain references to "Make variables".
additional_substitutions required
Additional substitutions to make beyond the default make variables.

features

list ctx.features

The set of features that are explicitly enabled by the user for this rule. See example of use.

file

struct ctx.file

A struct containing files defined in label type attributes marked as allow_single_file. The struct fields correspond to the attribute names. The struct value is always a File or None. If an optional attribute is not specified in the rule then the corresponding struct value is None. If a label type is not marked as allow_single_file, no corresponding struct field is generated. It is a shortcut for:
list(ctx.attr.<ATTR>.files)[0]
In other words, use file to access the (singular) default output of a dependency. See example of use.

files

struct ctx.files

A struct containing files defined in label or label list type attributes. The struct fields correspond to the attribute names. The struct values are list of Files. It is a shortcut for:
[f for t in ctx.attr.<ATTR> for f in t.files]
In other words, use files to access the default outputs of a dependency. See example of use.

fragments

fragments ctx.fragments

Allows access to configuration fragments in target configuration.

genfiles_dir

root ctx.genfiles_dir

The root corresponding to genfiles directory.

info_file

File ctx.info_file

The file that is used to hold the non-volatile workspace status for the current build request. See documentation for --workspace_status_command for more information.

label

Label ctx.label

The label of the target currently being analyzed.

outputs

structure ctx.outputs

A pseudo-struct containing all the predeclared output files, represented by File objects. See the Rules page for more information and examples.

This field does not exist on aspect contexts, since aspects do not have predeclared outputs.

The fields of this object are defined as follows. It is an error if two outputs produce the same field name or have the same label.

  • If the rule declares an outputs dict, then for every entry in the dict, there is a field whose name is the key and whose value is the corresponding File.
  • For every attribute of type attr.output that the rule declares, there is a field whose name is the attribute's name. If the target specified a label for that attribute, then the field value is the corresponding File; otherwise the field value is None.
  • For every attribute of type attr.output_list that the rule declares, there is a field whose name is the attribute's name. The field value is a list of File objects corresponding to the labels given for that attribute in the target, or an empty list if the attribute was not specified in the target.
  • (Deprecated) If the rule is marked executable or test, there is a field named "executable", which is the default executable. It is recommended that instead of using this, you pass another file (either predeclared or not) to the executable arg of DefaultInfo.

resolve_command

tuple ctx.resolve_command(command='', attribute=None, expand_locations=False, make_variables=None, tools=[], label_dict={}, execution_requirements={})

(Experimental) Returns a tuple (inputs, command, input_manifests) of the list of resolved inputs, the argv list for the resolved command, and the runfiles metadata required to run the command, all of them suitable for passing as the same-named arguments of the ctx.action method.
Note for Windows users: this method requires Bash (MSYS2). Consider using resolve_tools() instead (if that fits your needs).

Parameters

Parameter Description
command default is ''
Command to resolve.
attribute string; or None; default is None
Name of the associated attribute for which to issue an error, or None.
expand_locations default is False
Shall we expand $(location) variables? See ctx.expand_location() for more details.
make_variables dict; or None; default is None
Make variables to expand, or None.
tools sequence of Targets; default is []
List of tools (list of targets).
label_dict default is {}
Dictionary of resolved labels and the corresponding list of Files (a dict of Label : list of Files).
execution_requirements default is {}
Information for scheduling the action to resolve this command. See tags for useful keys.

resolve_tools

tuple ctx.resolve_tools(tools=[])

Returns a tuple (inputs, input_manifests) of the depset of resolved inputs and the runfiles metadata required to run the tools, both of them suitable for passing as the same-named arguments of the ctx.actions.run method.

In contrast to ctx.resolve_command, this method does not require that Bash be installed on the machine, so it's suitable for rules built on Windows.

Parameters

Parameter Description
tools sequence of Targets; default is []
List of tools (list of targets).

rule

rule_attributes ctx.rule

Rule attributes descriptor for the rule that the aspect is applied to. Only available in aspect implementation functions.

runfiles

runfiles ctx.runfiles(files=[], transitive_files=None, collect_data=False, collect_default=False, symlinks={}, root_symlinks={})

Creates a runfiles object.

Parameters

Parameter Description
files sequence of Files; default is []
The list of files to be added to the runfiles.
transitive_files depset of Files; or None; default is None
The (transitive) set of files to be added to the runfiles. The depset should use the default order (which, as the name implies, is the default).
collect_data default is False
Use of this parameter is not recommended. See runfiles guide.

Whether to collect the data runfiles from the dependencies in srcs, data and deps attributes.

collect_default default is False
Use of this parameter is not recommended. See runfiles guide.

Whether to collect the default runfiles from the dependencies in srcs, data and deps attributes.

dict; or depset of SymlinkEntrys; default is {}
Either a SymlinkEntry depset or the map of symlinks to be added to the runfiles. Symlinks are always added under the main workspace's runfiles directory (e.g. <runfiles_root>/_main/<symlink_path>, not the directory corresponding to the current target's repository. See Runfiles symlinks in the rules guide.
dict; or depset of SymlinkEntrys; default is {}
Either a SymlinkEntry depset or a map of symlinks to be added to the runfiles. See Runfiles symlinks in the rules guide.

split_attr

struct ctx.split_attr

A struct to access the values of attributes with split configurations. If the attribute is a label list, the value of split_attr is a dict of the keys of the split (as strings) to lists of the ConfiguredTargets in that branch of the split. If the attribute is a label, then the value of split_attr is a dict of the keys of the split (as strings) to single ConfiguredTargets. Attributes with split configurations still appear in the attr struct, but their values will be single lists with all the branches of the split merged together.

super

unknown ctx.super()

Experimental: Calls parent's implementation function and returns its providers

target_platform_has_constraint

bool ctx.target_platform_has_constraint(constraintValue)

Returns true if the given constraint value is part of the current target platform.

Parameters

Parameter Description
constraintValue required
The constraint value to check the target platform against.

toolchains

ToolchainContext ctx.toolchains

Toolchains for the default exec group of this rule.

var

dict ctx.var

Dictionary (String to String) of configuration variables.

version_file

File ctx.version_file

The file that is used to hold the volatile workspace status for the current build request. See documentation for --workspace_status_command for more information.

workspace_name

string ctx.workspace_name

The name of the workspace, which is effectively the execution root name and runfiles prefix for the main repo. If --enable_bzlmod is on, this is the fixed string _main. Otherwise, this is the workspace name as defined in the WORKSPACE file.