feat(strings): New functions TrimRight and TrimLeft (#2148)

Signed-off-by: Javier Solana javier.solana@cabify.com

Signed-off-by: Javier Solana javier.solana@cabify.com
Co-authored-by: Javier Solana <javier.solana@cabify.com>

4 files changed, 150 insertions, 0 deletions

diff --git a/docs-src/content/functions/strings.yml b/docs-src/content/functions/strings.yml
index 07378fb0..8c10a8f5 100644
--- a/docs-src/content/functions/strings.yml
+++ b/docs-src/content/functions/strings.yml
@@ -421,6 +421,23 @@ funcs:
       - |
         $ gomplate -i '{{ "_-foo-_" | strings.Trim "_-" }}'
         foo
+  - name: strings.TrimLeft
+    # released: v4.1.0
+    description: |
+      Trims a string by removing the given characters from the beginning of the string.
+      This wraps Go's [`strings.TrimLeft`](https://pkg.go.dev/strings#TrimLeft).
+    pipeline: true
+    arguments:
+      - name: cutset
+        required: true
+        description: the set of characters to cut
+      - name: input
+        required: true
+        description: the input
+    examples:
+      - |
+        $ gomplate -i '{{ "  - hello, world!" | strings.TrimLeft " " }}'
+        - hello, world!
   - name: strings.TrimPrefix
     released: v2.5.0
     description: |
@@ -439,6 +456,23 @@ funcs:
       - |
         $ gomplate -i '{{ "hello, world" | strings.TrimPrefix "hello, " }}'
         world
+  - name: strings.TrimRight
+    # released: v4.1.0
+    description: |
+      Trims a string by removing the given characters from the end of the string.
+      This wraps Go's [`strings.TrimRight`](https://pkg.go.dev/strings#TrimRight).
+    pipeline: true
+    arguments:
+      - name: cutset
+        required: true
+        description: the set of characters to cut
+      - name: input
+        required: true
+        description: the input
+    examples:
+      - |
+        $ gomplate -i '{{ "hello, world!  " | strings.TrimRight " " }}'
+        hello, world!
   - name: strings.TrimSpace
     alias: trimSpace
     released: v1.9.0
diff --git a/docs/content/functions/strings.md b/docs/content/functions/strings.md
index fe37830f..9ec1589a 100644
--- a/docs/content/functions/strings.md
+++ b/docs/content/functions/strings.md
@@ -669,6 +669,35 @@ $ gomplate -i '{{ "_-foo-_" | strings.Trim "_-" }}'
 foo
 ```
 
+## `strings.TrimLeft`_(unreleased)_
+**Unreleased:** _This function is in development, and not yet available in released builds of gomplate._
+
+Trims a string by removing the given characters from the beginning of the string.
+This wraps Go's [`strings.TrimLeft`](https://pkg.go.dev/strings#TrimLeft).
+
+### Usage
+
+```
+strings.TrimLeft cutset input
+```
+```
+input | strings.TrimLeft cutset
+```
+
+### Arguments
+
+| name | description |
+|------|-------------|
+| `cutset` | _(required)_ the set of characters to cut |
+| `input` | _(required)_ the input |
+
+### Examples
+
+```console
+$ gomplate -i '{{ "  - hello, world!" | strings.TrimLeft " " }}'
+- hello, world!
+```
+
 ## `strings.TrimPrefix`
 
 Returns a string without the provided leading prefix string, if the prefix is present.
@@ -699,6 +728,35 @@ $ gomplate -i '{{ "hello, world" | strings.TrimPrefix "hello, " }}'
 world
 ```
 
+## `strings.TrimRight`_(unreleased)_
+**Unreleased:** _This function is in development, and not yet available in released builds of gomplate._
+
+Trims a string by removing the given characters from the end of the string.
+This wraps Go's [`strings.TrimRight`](https://pkg.go.dev/strings#TrimRight).
+
+### Usage
+
+```
+strings.TrimRight cutset input
+```
+```
+input | strings.TrimRight cutset
+```
+
+### Arguments
+
+| name | description |
+|------|-------------|
+| `cutset` | _(required)_ the set of characters to cut |
+| `input` | _(required)_ the input |
+
+### Examples
+
+```console
+$ gomplate -i '{{ "hello, world!  " | strings.TrimRight " " }}'
+hello, world!
+```
+
 ## `strings.TrimSpace`
 
 **Alias:** `trimSpace`
diff --git a/internal/funcs/strings.go b/internal/funcs/strings.go
index cb440868..c07e0924 100644
--- a/internal/funcs/strings.go
+++ b/internal/funcs/strings.go
@@ -223,11 +223,21 @@ func (StringFuncs) Trim(cutset string, s interface{}) string {
 	return strings.Trim(conv.ToString(s), cutset)
 }
 
+// TrimLeft -
+func (StringFuncs) TrimLeft(cutset string, s interface{}) string {
+	return strings.TrimLeft(conv.ToString(s), cutset)
+}
+
 // TrimPrefix -
 func (StringFuncs) TrimPrefix(cutset string, s interface{}) string {
 	return strings.TrimPrefix(conv.ToString(s), cutset)
 }
 
+// TrimRight -
+func (StringFuncs) TrimRight(cutset string, s interface{}) string {
+	return strings.TrimRight(conv.ToString(s), cutset)
+}
+
 // TrimSuffix -
 func (StringFuncs) TrimSuffix(cutset string, s interface{}) string {
 	return strings.TrimSuffix(conv.ToString(s), cutset)
diff --git a/internal/funcs/strings_test.go b/internal/funcs/strings_test.go
index e1561a0c..032e45e3 100644
--- a/internal/funcs/strings_test.go
+++ b/internal/funcs/strings_test.go
@@ -256,3 +256,51 @@ func TestRuneCount(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, 5, n)
 }
+
+func TestTrimLeft(t *testing.T) {
+	t.Parallel()
+
+	sf := &StringFuncs{}
+
+	testdata := []struct {
+		in     interface{}
+		cutset string
+		out    string
+	}{
+		{``, ``, ``},
+		{`foo`, ``, `foo`},
+		{` foo`, ` `, `foo`},
+		{`  foo`, ` `, `foo`},
+		{`fooBAR`, `foo`, `BAR`},
+		{`-_fooBAR`, `-_`, `fooBAR`},
+	}
+
+	for _, d := range testdata {
+		trimmed := sf.TrimLeft(d.cutset, d.in)
+		assert.Equal(t, d.out, trimmed)
+	}
+}
+
+func TestTrimRight(t *testing.T) {
+	t.Parallel()
+
+	sf := &StringFuncs{}
+
+	testdata := []struct {
+		in     interface{}
+		cutset string
+		out    string
+	}{
+		{``, ``, ``},
+		{`foo`, ``, `foo`},
+		{`foo `, ` `, `foo`},
+		{`foo  `, ` `, `foo`},
+		{`fooBAR`, `BAR`, `foo`},
+		{`fooBAR-_`, `-_`, `fooBAR`},
+	}
+
+	for _, d := range testdata {
+		trimmed := sf.TrimRight(d.cutset, d.in)
+		assert.Equal(t, d.out, trimmed)
+	}
+}