Support TokenEscapeChar, add tests

template_nest.go

@@ -22,6 +22,7 @@ type Option struct {
 	ShowLabels        bool      // Prepend & Append a string to every template, helpful in debugging
 	CommentDelimiters [2]string // Used in conjunction with ShowLabels, if HTML then use '<!--', '-->'
 	FixedIndent       bool      // Intended to improve readability when inspecting nested templates
+	TokenEscapeChar   string    // Escapes a token delimiter, i.e. if set to '\' then variables that have '\' prefix won't be replaced
 }
 
 type TemplateNest struct {
@@ -131,6 +132,7 @@ func (nest *TemplateNest) index(filePath string) (TemplateFileIndex, error) {
 
 	delimiterStart := nest.option.Delimiters[0]
 	delimiterEnd := nest.option.Delimiters[1]
+	escapeChar := nest.option.TokenEscapeChar
 
 	re := regexp.MustCompile(fmt.Sprintf(
 		"%s\\s*(.+?)\\s*%s", regexp.QuoteMeta(delimiterStart), regexp.QuoteMeta(delimiterEnd),
@@ -151,6 +153,22 @@ func (nest *TemplateNest) index(filePath string) (TemplateFileIndex, error) {
 		varName := string(contents[nameStartIdx:nameEndIdx])
 		variableNames[varName] = struct{}{}
 
+		// If token escape char is set then look behind for it and if we
+		// find the escape char then we're only going to remove the escape
+		// char and not remove this variable.
+		if escapeChar != "" && startIdx >= len(escapeChar) {
+			escapeStartIdx := startIdx - len(escapeChar)
+			if contentsStr[escapeStartIdx:startIdx] == escapeChar {
+				variables = append(variables, TemplateFileVariable{
+					Name:          "",
+					StartPosition: uint(escapeStartIdx),
+					EndPosition:   uint(escapeStartIdx + len(escapeChar)),
+					EscapedToken:  true,
+				})
+				continue
+			}
+		}
+
 		// If fixed indent is enabled then record the indent level for this
 		// variable. To get the indent level we look at each character in
 		// reverse from the start position of the variable until we find a
@@ -276,6 +294,10 @@ func (nest *TemplateNest) Render(toRender interface{}) (string, error) {
 		rendered := tIndex.Contents
 		for i := len(tIndex.Variables) - 1; i >= 0; i-- {
 			variable := tIndex.Variables[i]
+			if variable.EscapedToken {
+				rendered = rendered[:variable.StartPosition] + rendered[variable.EndPosition:]
+				continue
+			}
 
 			// If the variable doesn't exist in template hash then replace it
 			// with an empty string.

tests/07_token_escape_char_test.go

@@ -0,0 +1,97 @@
+package tests
+
+import (
+	"git.virtual.blue/tomgracey/template-nest-go"
+	"github.com/stretchr/testify/assert"
+	"io/ioutil"
+	"strings"
+	"testing"
+)
+
+func TestRenderWithEscapedVariable(t *testing.T) {
+	nest, err := templatenest.New(templatenest.Option{
+		TemplateDir:     "templates",
+		TokenEscapeChar: "\\",
+	})
+	if err != nil {
+		t.Fatalf("Failed to initialize TemplateNest: %+v", err)
+	}
+
+	page := templatenest.Hash{
+		"TEMPLATE": "00-simple-page",
+		"variable": "Simple Variable",
+		"simple_component": []templatenest.Hash{
+			templatenest.Hash{
+				"TEMPLATE": "01-simple-component-token-escape",
+			},
+		},
+	}
+
+	outputPath := "templates/output/09-simple-page-token-escape.html"
+	outputContents, err := ioutil.ReadFile(outputPath)
+	if err != nil {
+		t.Fatalf("error reading file (`%s`): %+v", outputPath, err)
+	}
+
+	assert.Equal(
+		t,
+		strings.TrimSpace(string(outputContents)),
+		nest.MustRender(page),
+		"Rendered output does not match expected output",
+	)
+}
+
+func TestRenderWithEscapedVariableAtStart(t *testing.T) {
+	nest, err := templatenest.New(templatenest.Option{
+		TemplateDir:     "templates",
+		TokenEscapeChar: "\\",
+	})
+	if err != nil {
+		t.Fatalf("Failed to initialize TemplateNest: %+v", err)
+	}
+
+	page := templatenest.Hash{
+		"TEMPLATE": "03-var-at-begin",
+		"variable": "Simple Variable",
+	}
+
+	outputPath := "templates/output/10-var-at-begin.html"
+	outputContents, err := ioutil.ReadFile(outputPath)
+	if err != nil {
+		t.Fatalf("error reading file (`%s`): %+v", outputPath, err)
+	}
+
+	assert.Equal(
+		t,
+		strings.TrimSpace(string(outputContents)),
+		nest.MustRender(page),
+		"Rendered output does not match expected output",
+	)
+}
+
+func TestRenderWithEscapedVariableAtStart01(t *testing.T) {
+	nest, err := templatenest.New(templatenest.Option{
+		TemplateDir:     "templates",
+		TokenEscapeChar: "\\",
+	})
+	if err != nil {
+		t.Fatalf("Failed to initialize TemplateNest: %+v", err)
+	}
+
+	page := templatenest.Hash{
+		"TEMPLATE": "03-var-at-begin-with-space",
+	}
+
+	outputPath := "templates/output/10-var-at-begin-with-space.html"
+	outputContents, err := ioutil.ReadFile(outputPath)
+	if err != nil {
+		t.Fatalf("error reading file (`%s`): %+v", outputPath, err)
+	}
+
+	assert.Equal(
+		t,
+		strings.TrimSpace(string(outputContents)),
+		nest.MustRender(page),
+		"Rendered output does not match expected output",
+	)
+}

tests/templates/03-var-at-begin-with-space.html

@@ -0,0 +1 @@
+\<!--% variable %-->

tests/templates/output/10-var-at-begin-with-space.html

@@ -0,0 +1 @@
+<!--% variable %-->