ctx

使用集合让一切井井有条 根据您的偏好保存内容并对其进行分类。
传递给规则或方面实现函数的上下文对象。可用于访问分析当前目标所需的信息和方法。

具体来说,它可让实现函数访问当前目标的标签、属性、配置及其依赖项的提供程序。其中包含用于声明输出文件及其生成操作的方法。

上下文对象实质上在调用实现函数期间存在。在相关函数之外访问这些对象没有用。如需了解详情,请参阅“规则”页面

会员

操作

actions ctx.actions

包含用于声明输出文件的方法以及生成这些文件的操作。

宽高比 ID

list ctx.aspect_ids

应用于目标的所有方面的 ID 列表。仅在宽高比实现函数中提供。

属性

struct ctx.attr

用于访问属性值的结构体。这些值由用户提供(如果不是默认值,则使用默认值)。结构体的属性及其值与提供给 rule 函数attrs dict 的键和值相对应。查看使用示例

bin_dir

root ctx.bin_dir

与 bin 目录对应的根目录。

build_file_path

string ctx.build_file_path

此规则相对于源代码根目录的 BUILD 文件路径。

build_setting_value

unknown ctx.build_setting_value

实验性。此字段目前处于实验阶段,可能会随时发生变化。请勿依赖它。

由当前目标表示的构建设置的值。对于未在规则定义中设置 build_setting 属性的规则,访问此字段是错误的。

配置

configuration ctx.configuration

默认配置。如需了解详情,请参阅配置类型。

覆盖率插桩

bool ctx.coverage_instrumented(target=None)

返回在执行此规则的编译操作时是否应生成代码覆盖率插桩,如果提供了 target,则返回该目标指定的规则。(如果提供了非规则或 Starlark 规则目标,则返回 False。)检查当前规则的来源(如果未提供目标)或目标来源是否应根据 --instrumentation_filter 和 --instrument_test_targets 配置设置进行插桩。这与配置中的 coverage_enabled 不同,后者用于说明整个运行是否启用了覆盖率数据收集,但并未指明是否应对特定目标进行插桩。

参数

参数 说明
target Target; or None;默认值 = None
指定规则的目标。如果未提供,则默认为当前规则。

已创建操作

StarlarkValue ctx.created_actions()

对于 _skylark_testable 设置为 True 的规则,此方法会返回 Actions 提供程序,该提供程序表示为当前规则创建的所有操作。对于所有其他规则,则返回 None。请注意,在创建后续操作时,提供程序不会更新,因此如果您想要检查提供程序,必须再次调用此函数。

本功能旨在帮助编写针对规则实现辅助函数的测试,这类函数可以接受 ctx 对象并对其执行操作。

默认提供程序

Provider ctx.default_provider

已弃用。请改用 DefaultInfo

已停用的功能

list ctx.disabled_features

用户针对此规则明确停用的一组功能。

exec_groups

ExecGroupCollection ctx.exec_groups

可用于此规则的执行组的集合,按其名称编入索引。通过 ctx.exec_groups[name_of_group] 访问。

可执行

struct ctx.executable

struct,包含标签类型属性中定义的可执行文件,标记为 executable=True。结构体字段与属性名称相对应。结构体中的每个值都是 FileNone。如果规则中未指定某个可选属性,则相应的结构体值为 None。如果未将标签类型标记为 executable=True,则不会生成相应的结构体字段。查看使用示例

展开位置

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

通过将 $(location //x) 替换为目标 //x 的输出文件的路径,扩展给定字符串中的所有 $(location ...) 模板。展开功能仅适用于指向此规则的直接依赖项的标签,或明确包含在可选参数 targets 中的标签。

如果引用的目标有多个输出,$(location ...) 就会引发错误。在这种情况下,请使用 $(locations ...),因为它会生成以空格分隔的输出路径列表。也可以安全地用于单个输出文件。

借助该函数,用户可以在 BUILD 文件中指定命令(例如针对 genrule)。在其他情况下,直接操控标签通常更为方便。

参数

参数 说明
input 必需
要扩展的字符串。
targets sequence of Targets;默认值为 []
。包含其他查找信息的目标列表。
short_paths default = False
使用根相对路径,而不是完整的执行路径
可能会返回 None

展开变量

string ctx.expand_make_variables(attribute_name, command, additional_substitutions)

已弃用。请改用 ctx.var 访问变量。
在扩展对“Make Variables”的所有引用后,返回一个字符串。变量必须采用以下格式:$(VAR_NAME)。此外,$$VAR_NAME expands to $VAR_NAME. Examples:
ctx.expand_make_variables("cmd", "$(MY_VAR)", {"MY_VAR": "Hi"})  # == "Hi"
ctx.expand_make_variables("cmd", "$$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.

host_configuration

configuration ctx.host_configuration

The host configuration. See the configuration type for more details.

host_fragments

fragments ctx.host_fragments

Allows access to configuration fragments in host configuration.

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.

new_file

File ctx.new_file(var1, var2=unbound, var3=unbound)

DEPRECATED. Use ctx.actions.declare_file.
Creates a file object. There are four possible signatures to this method:
  • new_file(filename): Creates a file object with the given filename in the current package.
  • new_file(file_root, filename): Creates a file object with the given filename under the given file root.
  • new_file(sibling_file, filename): Creates a file object in the same directory as the given sibling file.
  • new_file(file_root, sibling_file, suffix): Creates a file object with same base name of the sibling_file but with different given suffix, under the given file root.

Does not actually create a file on the file system, just declares that some action will do so. You must create an action that generates the file. If the file should be visible to other rules, declare a rule output instead when possible. Doing so enables Blaze to associate a label with the file that rules can refer to (allowing finer dependency control) instead of referencing the whole rule.

Parameters

Parameter Description
var1 string; or root; or File; required
var2 string; or File; default = unbound
var3 string; default = unbound

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 = ''
Command to resolve.
attribute string; or None; default = None
Name of the associated attribute for which to issue an error, or None.
expand_locations default = False
Shall we expand $(location) variables? See ctx.expand_location() for more details.
make_variables dict; or None; default = None
Make variables to expand, or None.
tools sequence of Targets; default = []
List of tools (list of targets).
label_dict default = {}
Dictionary of resolved labels and the corresponding list of Files (a dict of Label : list of Files).
execution_requirements default = {}
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 = []
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 = []
The list of files to be added to the runfiles.
transitive_files depset of Files; or None; default = 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 = 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 = 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 = {}
Either a SymlinkEntry depset or the map of symlinks, prefixed by workspace name, to be added to the runfiles. See Runfiles symlinks in the rules guide.
dict; or depset of SymlinkEntrys; default = {}
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.

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 workspace name as defined in the WORKSPACE file.