docs/howto: use path.{Base,Dir,Ext} to examine paths

This adds a Commented CUE guide that demonstrates how to use path.Base, path.Dir, and path.Ext to access components of a file's name and path. A single guide was preferred, rather than 3 separate documents, to more accessibly display the relationship and potential overlap between the values the functions emit when given specific inputs. Only one example is laid out in full to demonstrate the function calls, at the top of the guide. Several examples are added via comprehensions in order to provide the reader with information about potential corner case output. The OS flavour parameter is deliberately *not* incorporated into a top-level loop so that the reader has direct visibility into the form that Windows path-specific function calls take; without having to mentally unroll the putative loop to infer the "path.Windows" value. Preview-Path: /docs/howto/use-the-built-in-functions-path-base-path-dir-path-ext-to-examine-path-filename-components/ Signed-off-by: Jonathan Matthews <[email protected]> Change-Id: I0c80c4fea19b018c902bcc3ffecefb7509083ca1
cue-lang · Jan 22, 2024 · d746bbe · d746bbe
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diff --git a/...functions-path-base-path-dir-path-ext-to-examine-path-filename-components/en.md b/...functions-path-base-path-dir-path-ext-to-examine-path-filename-components/en.md
@@ -0,0 +1,182 @@
+---
+title: Using the built-in functions "path.Base", "path.Dir", and "path.Ext" to examine path and filename components
+tags:
+- commented cue
+authors:
+- jpluscplusm
+toc_hide: true
+---
+
+This [Commented CUE]({{< relref "docs/howto#commented-cue-guides" >}})
+demonstrates how to use the built-in functions
+[`path.Base`](https://pkg.go.dev/cuelang.org/go/pkg/path#Base),
+[`path.Dir`](https://pkg.go.dev/cuelang.org/go/pkg/path#Dir), and
+[`path.Ext`](https://pkg.go.dev/cuelang.org/go/pkg/path#Ext)
+to access components of a file's name and its path.
+
+{{{with code "en" "cc"}}}
+# eval is used so the output's leaf values are horizontally aligned, allowing
+# the user to more easily compare "Path" and "Dir" values visually
+exec cue eval -e output
+cmp stdout out
+-- file.cue --
+package example
+
+import "path"
+
+output: unix: fileAbsolutePath: {
+	Path: "/foo/bar/baz.js"
+
+	// path.Dir, path.Base and path.Ext need
+	// to be told their input path's OS type,
+	// via their 2nd parameter
+
+	// path.Dir emits every component of the
+	// path's directory
+	Dir: path.Dir(Path, path.Unix)
+
+	// path.Base emits the path's final
+	// component, regardless of if it
+	// represents a file or a directory
+	Base: path.Base(Path, path.Unix)
+
+	// path.Ext emits the path's filename
+	// extension, but *only* if the path
+	// represents a file
+	Ext: path.Ext(Path, path.Unix)
+}
+
+examples: unix: {
+	fileAbsolutePath: "/foo/bar/baz.js"
+	fileRelativePath: "bar/baz.js.backup"
+	fileNoExtension:  "/foo/bar/baz"
+	dirAbsolutePath:  "/foo/bar/baz/"
+	dirWithExtension: "/foo/bar/baz.dir/"
+	dirWithTraversal: "/foo/bar/../quux/a.js"
+	fileDirtyPath:    "/foo///bar////baz.js"
+}
+examples: windows: {
+	fileAbsolutePath: #"C:\foo\bar\baz.js"#
+	fileRelativePath: #"bar\baz.js.backup"#
+	fileNoExtension:  #"C:\foo\bar\baz"#
+	dirAbsolutePath:  #"C:\foo\bar\baz\"#
+	dirWithExtension: #"C:\foo\bar\baz.dir\"#
+	dirWithTraversal: #"C:\foo\bar\..\quux\a.js"#
+	fileDirtyPath:    #"C:\foo\\bar\\\baz.js"#
+}
+
+output: unix: {for _id, _path in examples.unix {(_id): {
+	Path: _path
+	Dir:  path.Dir(_path, path.Unix)
+	Base: path.Base(_path, path.Unix)
+	Ext:  path.Ext(_path, path.Unix)
+}}}
+output: windows: {for _id, _path in examples.windows {(_id): {
+	Path: _path
+	Dir:  path.Dir(_path, path.Windows)
+	Base: path.Base(_path, path.Windows)
+	Ext:  path.Ext(_path, path.Windows)
+}}}
+-- out --
+unix: {
+    fileAbsolutePath: {
+        Path: "/foo/bar/baz.js"
+        Dir:  "/foo/bar"
+        Base: "baz.js"
+        Ext:  ".js"
+    }
+    fileRelativePath: {
+        Path: "bar/baz.js.backup"
+        Dir:  "bar"
+        Base: "baz.js.backup"
+        Ext:  ".backup"
+    }
+    fileNoExtension: {
+        Path: "/foo/bar/baz"
+        Dir:  "/foo/bar"
+        Base: "baz"
+        Ext:  ""
+    }
+    dirAbsolutePath: {
+        Path: "/foo/bar/baz/"
+        Dir:  "/foo/bar/baz"
+        Base: "baz"
+        Ext:  ""
+    }
+    dirWithExtension: {
+        Path: "/foo/bar/baz.dir/"
+        Dir:  "/foo/bar/baz.dir"
+        Base: "baz.dir"
+        Ext:  ""
+    }
+    dirWithTraversal: {
+        Path: "/foo/bar/../quux/a.js"
+        Dir:  "/foo/quux"
+        Base: "a.js"
+        Ext:  ".js"
+    }
+    fileDirtyPath: {
+        Path: "/foo///bar////baz.js"
+        Dir:  "/foo/bar"
+        Base: "baz.js"
+        Ext:  ".js"
+    }
+}
+windows: {
+    fileAbsolutePath: {
+        Path: "C:\\foo\\bar\\baz.js"
+        Dir:  "C:\\foo\\bar"
+        Base: "baz.js"
+        Ext:  ".js"
+    }
+    fileRelativePath: {
+        Path: "bar\\baz.js.backup"
+        Dir:  "bar"
+        Base: "baz.js.backup"
+        Ext:  ".backup"
+    }
+    fileNoExtension: {
+        Path: "C:\\foo\\bar\\baz"
+        Dir:  "C:\\foo\\bar"
+        Base: "baz"
+        Ext:  ""
+    }
+    dirAbsolutePath: {
+        Path: "C:\\foo\\bar\\baz\\"
+        Dir:  "C:\\foo\\bar\\baz"
+        Base: "baz"
+        Ext:  ""
+    }
+    dirWithExtension: {
+        Path: "C:\\foo\\bar\\baz.dir\\"
+        Dir:  "C:\\foo\\bar\\baz.dir"
+        Base: "baz.dir"
+        Ext:  ""
+    }
+    dirWithTraversal: {
+        Path: "C:\\foo\\bar\\..\\quux\\a.js"
+        Dir:  "C:\\foo\\quux"
+        Base: "a.js"
+        Ext:  ".js"
+    }
+    fileDirtyPath: {
+        Path: "C:\\foo\\\\bar\\\\\\baz.js"
+        Dir:  "C:\\foo\\bar"
+        Base: "baz.js"
+        Ext:  ".js"
+    }
+}
+{{{end}}}
+
+## Related content
+
+- The [`path`](https://pkg.go.dev/cuelang.org/go/pkg/path) built-in package
+  documentation details the rules that each of the functions
+  [`path.Base`](https://pkg.go.dev/cuelang.org/[email protected]/pkg/path#Base),
+  [`path.Dir`](https://pkg.go.dev/cuelang.org/[email protected]/pkg/path#Dir), and
+  [`path.Ext`](https://pkg.go.dev/cuelang.org/[email protected]/pkg/path#Ext) follow
+  as they process their input
+- Using CUE's ["raw" strings]({{< relref "docs/tour/types/stringraw" >}}) is
+  convenient when writing literal Windows paths. They avoid having to escape
+  every backslash (`\\`) - as is demonstrated above in the `examples.windows`
+  struct inside `file.cue`
diff --git a/...n-functions-path-base-path-dir-path-ext-to-examine-path-filename-components/gen_cache.cue b/...n-functions-path-base-path-dir-path-ext-to-examine-path-filename-components/gen_cache.cue
@@ -0,0 +1,18 @@
+package site
+{
+	content: {
+		docs: {
+			howto: {
+				"use-the-built-in-functions-path-base-path-dir-path-ext-to-examine-path-filename-components": {
+					page: {
+						cache: {
+							code: {
+								cc: "Rf1XI25CxOVp9/NGjQz3elOoablgz2OTWIPxWkgH96w="
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+}
diff --git a/...ilt-in-functions-path-base-path-dir-path-ext-to-examine-path-filename-components/page.cue b/...ilt-in-functions-path-base-path-dir-path-ext-to-examine-path-filename-components/page.cue
@@ -0,0 +1,3 @@
+package site
+
+content: docs: howto: "use-the-built-in-functions-path-base-path-dir-path-ext-to-examine-path-filename-components": {}
diff --git a/...ctions-path-base-path-dir-path-ext-to-examine-path-filename-components/index.md b/...ctions-path-base-path-dir-path-ext-to-examine-path-filename-components/index.md
@@ -0,0 +1,181 @@
+---
+title: Using the built-in functions "path.Base", "path.Dir", and "path.Ext" to examine path and filename components
+tags:
+- commented cue
+authors:
+- jpluscplusm
+toc_hide: true
+---
+
+This [Commented CUE]({{< relref "docs/howto#commented-cue-guides" >}})
+demonstrates how to use the built-in functions
+[`path.Base`](https://pkg.go.dev/cuelang.org/go/pkg/path#Base),
+[`path.Dir`](https://pkg.go.dev/cuelang.org/go/pkg/path#Dir), and
+[`path.Ext`](https://pkg.go.dev/cuelang.org/go/pkg/path#Ext)
+to access components of a file's name and its path.
+
+{{< code-tabs >}}
+{{< code-tab name="file.cue" language="cue"  area="top-left" >}}
+package example
+
+import "path"
+
+output: unix: fileAbsolutePath: {
+	Path: "/foo/bar/baz.js"
+
+	// path.Dir, path.Base and path.Ext need
+	// to be told their input path's OS type,
+	// via their 2nd parameter
+
+	// path.Dir emits every component of the
+	// path's directory
+	Dir: path.Dir(Path, path.Unix)
+
+	// path.Base emits the path's final
+	// component, regardless of if it
+	// represents a file or a directory
+	Base: path.Base(Path, path.Unix)
+
+	// path.Ext emits the path's filename
+	// extension, but *only* if the path
+	// represents a file
+	Ext: path.Ext(Path, path.Unix)
+}
+
+examples: unix: {
+	fileAbsolutePath: "/foo/bar/baz.js"
+	fileRelativePath: "bar/baz.js.backup"
+	fileNoExtension:  "/foo/bar/baz"
+	dirAbsolutePath:  "/foo/bar/baz/"
+	dirWithExtension: "/foo/bar/baz.dir/"
+	dirWithTraversal: "/foo/bar/../quux/a.js"
+	fileDirtyPath:    "/foo///bar////baz.js"
+}
+examples: windows: {
+	fileAbsolutePath: #"C:\foo\bar\baz.js"#
+	fileRelativePath: #"bar\baz.js.backup"#
+	fileNoExtension:  #"C:\foo\bar\baz"#
+	dirAbsolutePath:  #"C:\foo\bar\baz\"#
+	dirWithExtension: #"C:\foo\bar\baz.dir\"#
+	dirWithTraversal: #"C:\foo\bar\..\quux\a.js"#
+	fileDirtyPath:    #"C:\foo\\bar\\\baz.js"#
+}
+
+output: unix: {for _id, _path in examples.unix {(_id): {
+	Path: _path
+	Dir:  path.Dir(_path, path.Unix)
+	Base: path.Base(_path, path.Unix)
+	Ext:  path.Ext(_path, path.Unix)
+}}}
+output: windows: {for _id, _path in examples.windows {(_id): {
+	Path: _path
+	Dir:  path.Dir(_path, path.Windows)
+	Base: path.Base(_path, path.Windows)
+	Ext:  path.Ext(_path, path.Windows)
+}}}
+{{< /code-tab >}}
+{{< code-tab name="TERMINAL" language="" type="terminal" area="top-right" >}}
+$ cue eval -e output
+unix: {
+    fileAbsolutePath: {
+        Path: "/foo/bar/baz.js"
+        Dir:  "/foo/bar"
+        Base: "baz.js"
+        Ext:  ".js"
+    }
+    fileRelativePath: {
+        Path: "bar/baz.js.backup"
+        Dir:  "bar"
+        Base: "baz.js.backup"
+        Ext:  ".backup"
+    }
+    fileNoExtension: {
+        Path: "/foo/bar/baz"
+        Dir:  "/foo/bar"
+        Base: "baz"
+        Ext:  ""
+    }
+    dirAbsolutePath: {
+        Path: "/foo/bar/baz/"
+        Dir:  "/foo/bar/baz"
+        Base: "baz"
+        Ext:  ""
+    }
+    dirWithExtension: {
+        Path: "/foo/bar/baz.dir/"
+        Dir:  "/foo/bar/baz.dir"
+        Base: "baz.dir"
+        Ext:  ""
+    }
+    dirWithTraversal: {
+        Path: "/foo/bar/../quux/a.js"
+        Dir:  "/foo/quux"
+        Base: "a.js"
+        Ext:  ".js"
+    }
+    fileDirtyPath: {
+        Path: "/foo///bar////baz.js"
+        Dir:  "/foo/bar"
+        Base: "baz.js"
+        Ext:  ".js"
+    }
+}
+windows: {
+    fileAbsolutePath: {
+        Path: "C:\\foo\\bar\\baz.js"
+        Dir:  "C:\\foo\\bar"
+        Base: "baz.js"
+        Ext:  ".js"
+    }
+    fileRelativePath: {
+        Path: "bar\\baz.js.backup"
+        Dir:  "bar"
+        Base: "baz.js.backup"
+        Ext:  ".backup"
+    }
+    fileNoExtension: {
+        Path: "C:\\foo\\bar\\baz"
+        Dir:  "C:\\foo\\bar"
+        Base: "baz"
+        Ext:  ""
+    }
+    dirAbsolutePath: {
+        Path: "C:\\foo\\bar\\baz\\"
+        Dir:  "C:\\foo\\bar\\baz"
+        Base: "baz"
+        Ext:  ""
+    }
+    dirWithExtension: {
+        Path: "C:\\foo\\bar\\baz.dir\\"
+        Dir:  "C:\\foo\\bar\\baz.dir"
+        Base: "baz.dir"
+        Ext:  ""
+    }
+    dirWithTraversal: {
+        Path: "C:\\foo\\bar\\..\\quux\\a.js"
+        Dir:  "C:\\foo\\quux"
+        Base: "a.js"
+        Ext:  ".js"
+    }
+    fileDirtyPath: {
+        Path: "C:\\foo\\\\bar\\\\\\baz.js"
+        Dir:  "C:\\foo\\bar"
+        Base: "baz.js"
+        Ext:  ".js"
+    }
+}
+{{< /code-tab >}}
+{{< /code-tabs >}}
+
+## Related content
+
+- The [`path`](https://pkg.go.dev/cuelang.org/go/pkg/path) built-in package
+  documentation details the rules that each of the functions
+  [`path.Base`](https://pkg.go.dev/cuelang.org/[email protected]/pkg/path#Base),
+  [`path.Dir`](https://pkg.go.dev/cuelang.org/[email protected]/pkg/path#Dir), and
+  [`path.Ext`](https://pkg.go.dev/cuelang.org/[email protected]/pkg/path#Ext) follow
+  as they process their input
+- Using CUE's ["raw" strings]({{< relref "docs/tour/types/stringraw" >}}) is
+  convenient when writing literal Windows paths. They avoid having to escape
+  every backslash (`\\`) - as is demonstrated above in the `examples.windows`
+  struct inside `file.cue`
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,3 @@
		package site

		content: docs: howto: "use-the-built-in-functions-path-base-path-dir-path-ext-to-examine-path-filename-components": {}