lang/funcs: Add more `trim*` functions (#23016)

* lang/funcs: Add `trim*` functions

lang/funcs/string.go

@@ -123,7 +123,7 @@ var SplitFunc = function.New(&function.Spec{
 	},
 })
 
-// ChompFunc constructions a function that removes newline characters at the end of a string.
+// ChompFunc constructs a function that removes newline characters at the end of a string.
 var ChompFunc = function.New(&function.Spec{
 	Params: []function.Parameter{
 		{
@@ -138,7 +138,7 @@ var ChompFunc = function.New(&function.Spec{
 	},
 })
 
-// IndentFunc constructions a function that adds a given number of spaces to the
+// IndentFunc constructs a function that adds a given number of spaces to the
 // beginnings of all but the first line in a given multi-line string.
 var IndentFunc = function.New(&function.Spec{
 	Params: []function.Parameter{
@@ -163,7 +163,7 @@ var IndentFunc = function.New(&function.Spec{
 	},
 })
 
-// ReplaceFunc constructions a function that searches a given string for another
+// ReplaceFunc constructs a function that searches a given string for another
 // given substring, and replaces each occurence with a given replacement string.
 var ReplaceFunc = function.New(&function.Spec{
 	Params: []function.Parameter{
@@ -201,7 +201,7 @@ var ReplaceFunc = function.New(&function.Spec{
 	},
 })
 
-// TitleFunc constructions a function that converts the first letter of each word
+// TitleFunc constructs a function that converts the first letter of each word
 // in the given string to uppercase.
 var TitleFunc = function.New(&function.Spec{
 	Params: []function.Parameter{
@@ -216,7 +216,7 @@ var TitleFunc = function.New(&function.Spec{
 	},
 })
 
-// TrimSpaceFunc constructions a function that removes any space characters from
+// TrimSpaceFunc constructs a function that removes any space characters from
 // the start and end of the given string.
 var TrimSpaceFunc = function.New(&function.Spec{
 	Params: []function.Parameter{
@@ -231,6 +231,69 @@ var TrimSpaceFunc = function.New(&function.Spec{
 	},
 })
 
+// TrimFunc constructs a function that removes the specified characters from
+// the start and end of the given string.
+var TrimFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "str",
+			Type: cty.String,
+		},
+		{
+			Name: "cutset",
+			Type: cty.String,
+		},
+	},
+	Type: function.StaticReturnType(cty.String),
+	Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
+		str := args[0].AsString()
+		cutset := args[1].AsString()
+		return cty.StringVal(strings.Trim(str, cutset)), nil
+	},
+})
+
+// TrimPrefixFunc constructs a function that removes the specified characters from
+// the start the given string.
+var TrimPrefixFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "str",
+			Type: cty.String,
+		},
+		{
+			Name: "prefix",
+			Type: cty.String,
+		},
+	},
+	Type: function.StaticReturnType(cty.String),
+	Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
+		str := args[0].AsString()
+		prefix := args[1].AsString()
+		return cty.StringVal(strings.TrimPrefix(str, prefix)), nil
+	},
+})
+
+// TrimSuffixFunc constructs a function that removes the specified characters from
+// the end of the given string.
+var TrimSuffixFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "str",
+			Type: cty.String,
+		},
+		{
+			Name: "suffix",
+			Type: cty.String,
+		},
+	},
+	Type: function.StaticReturnType(cty.String),
+	Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
+		str := args[0].AsString()
+		cutset := args[1].AsString()
+		return cty.StringVal(strings.TrimSuffix(str, cutset)), nil
+	},
+})
+
 // Join concatenates together the string elements of one or more lists with a
 // given separator.
 func Join(sep cty.Value, lists ...cty.Value) (cty.Value, error) {
@@ -278,3 +341,18 @@ func Title(str cty.Value) (cty.Value, error) {
 func TrimSpace(str cty.Value) (cty.Value, error) {
 	return TrimSpaceFunc.Call([]cty.Value{str})
 }
+
+// Trim removes the specified characters from the start and end of the given string.
+func Trim(str, cutset cty.Value) (cty.Value, error) {
+	return TrimFunc.Call([]cty.Value{str, cutset})
+}
+
+// TrimPrefix removes the specified prefix from the start of the given string.
+func TrimPrefix(str, prefix cty.Value) (cty.Value, error) {
+	return TrimPrefixFunc.Call([]cty.Value{str, prefix})
+}
+
+// TrimSuffix removes the specified suffix from the end of the given string.
+func TrimSuffix(str, suffix cty.Value) (cty.Value, error) {
+	return TrimSuffixFunc.Call([]cty.Value{str, suffix})
+}

lang/funcs/string_test.go

@@ -506,3 +506,126 @@ func TestTrimSpace(t *testing.T) {
 		})
 	}
 }
+
+func TestTrim(t *testing.T) {
+	tests := []struct {
+		String cty.Value
+		Cutset cty.Value
+		Want   cty.Value
+		Err    bool
+	}{
+		{
+			cty.StringVal("!? test ?!"),
+			cty.StringVal("?!"),
+			cty.StringVal(" test "),
+			false,
+		},
+		{
+			cty.StringVal("...test..."),
+			cty.StringVal("."),
+			cty.StringVal("test"),
+			false,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("trim(%#v, %#v)", test.String, test.Cutset), func(t *testing.T) {
+			got, err := Trim(test.String, test.Cutset)
+
+			if test.Err {
+				if err == nil {
+					t.Fatal("succeeded; want error")
+				}
+				return
+			} else if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+
+			if !got.RawEquals(test.Want) {
+				t.Errorf("wrong result\ngot:  %#v\nwant: %#v", got, test.Want)
+			}
+		})
+	}
+}
+
+func TestTrimPrefix(t *testing.T) {
+	tests := []struct {
+		String cty.Value
+		Prefix cty.Value
+		Want   cty.Value
+		Err    bool
+	}{
+		{
+			cty.StringVal("helloworld"),
+			cty.StringVal("hello"),
+			cty.StringVal("world"),
+			false,
+		},
+		{
+			cty.StringVal("...test..."),
+			cty.StringVal("."),
+			cty.StringVal("..test..."),
+			false,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("trimprefix(%#v, %#v)", test.String, test.Prefix), func(t *testing.T) {
+			got, err := TrimPrefix(test.String, test.Prefix)
+
+			if test.Err {
+				if err == nil {
+					t.Fatal("succeeded; want error")
+				}
+				return
+			} else if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+
+			if !got.RawEquals(test.Want) {
+				t.Errorf("wrong result\ngot:  %#v\nwant: %#v", got, test.Want)
+			}
+		})
+	}
+}
+
+func TestTrimSuffix(t *testing.T) {
+	tests := []struct {
+		String cty.Value
+		Suffix cty.Value
+		Want   cty.Value
+		Err    bool
+	}{
+		{
+			cty.StringVal("helloworld"),
+			cty.StringVal("world"),
+			cty.StringVal("hello"),
+			false,
+		},
+		{
+			cty.StringVal("...test..."),
+			cty.StringVal("."),
+			cty.StringVal("...test.."),
+			false,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("trimright(%#v, %#v)", test.String, test.Suffix), func(t *testing.T) {
+			got, err := TrimSuffix(test.String, test.Suffix)
+
+			if test.Err {
+				if err == nil {
+					t.Fatal("succeeded; want error")
+				}
+				return
+			} else if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+
+			if !got.RawEquals(test.Want) {
+				t.Errorf("wrong result\ngot:  %#v\nwant: %#v", got, test.Want)
+			}
+		})
+	}
+}

website/docs/configuration/functions/trim.html.md

@@ -0,0 +1,31 @@
+---
+layout: "functions"
+page_title: "trim - Functions - Configuration Language"
+sidebar_current: "docs-funcs-string-trim"
+description: |-
+  The trim function removes the specified characters from the start and end of
+  a given string.
+---
+
+# `trim` Function
+
+-> **Note:** This page is about Terraform 0.12 and later. For Terraform 0.11 and
+earlier, see
+[0.11 Configuration Language: Interpolation Syntax](../../configuration-0-11/interpolation.html).
+
+`trim` removes the specified characters from the start and end of the given
+string.
+
+## Examples
+
+```
+> trim("?!hello?!", "!?")
+hello
+```
+
+## Related Functions
+
+* [`trimprefix`](./trimprefix.html) removes a word from the start of a string.
+* [`trimsuffix`](./trimsuffix.html) removes a word from the end of a string.
+* [`trimspace`](./trimspace.html) removes all types of whitespace from
+  both the start and the end of a string.

website/docs/configuration/functions/trimprefix.html.md

@@ -0,0 +1,30 @@
+---
+layout: "functions"
+page_title: "trimprefix - Functions - Configuration Language"
+sidebar_current: "docs-funcs-string-trimprefix"
+description: |-
+  The trimprefix function removes the specified prefix from the start of a
+  given string.
+---
+
+# `trimprefix` Function
+
+-> **Note:** This page is about Terraform 0.12 and later. For Terraform 0.11 and
+earlier, see
+[0.11 Configuration Language: Interpolation Syntax](../../configuration-0-11/interpolation.html).
+
+`trimprefix` removes the specified prefix from the start of the given string.
+
+## Examples
+
+```
+> trimprefix("helloworld", "hello")
+world
+```
+
+## Related Functions
+
+* [`trim`](./trim.html) removes characters at the start and end of a string.
+* [`trimsuffix`](./trimsuffix.html) removes a word from the end of a string.
+* [`trimspace`](./trimspace.html) removes all types of whitespace from
+  both the start and the end of a string.

website/docs/configuration/functions/trimsuffix.html.md

@@ -0,0 +1,30 @@
+---
+layout: "functions"
+page_title: "trimsuffix - Functions - Configuration Language"
+sidebar_current: "docs-funcs-string-trimsuffix"
+description: |-
+  The trimsuffix function removes the specified suffix from the end of a
+  given string.
+---
+
+# `trimsuffix` Function
+
+-> **Note:** This page is about Terraform 0.12 and later. For Terraform 0.11 and
+earlier, see
+[0.11 Configuration Language: Interpolation Syntax](../../configuration-0-11/interpolation.html).
+
+`trimsuffix` removes the specified suffix from the end of the given string.
+
+## Examples
+
+```
+> trimsuffix("helloworld", "world")
+hello
+```
+
+## Related Functions
+
+* [`trim`](./trim.html) removes characters at the start and end of a string.
+* [`trimprefix`](./trimprefix.html) removes a word from the start of a string.
+* [`trimspace`](./trimspace.html) removes all types of whitespace from
+  both the start and the end of a string.

website/layouts/functions.erb

@@ -111,6 +111,18 @@
                 <a href="/docs/configuration/functions/title.html">title</a>
               </li>
 
+              <li>
+                <a href="/docs/configuration/functions/trim.html">trim</a>
+              </li>
+
+              <li>
+                <a href="/docs/configuration/functions/trimprefix.html">trimprefix</a>
+              </li>
+
+              <li>
+                <a href="/docs/configuration/functions/trimsuffix.html">trimsuffix</a>
+              </li>
+
               <li>
                 <a href="/docs/configuration/functions/trimspace.html">trimspace</a>
               </li>