Move filters to own package

chunks/render.go

@@ -46,7 +46,7 @@ func (ctx Context) RenderASTSequence(w io.Writer, seq []ASTNode) error {
 // Render evaluates an AST node and writes the result to an io.Writer.
 func (n *ASTControlTag) Render(w io.Writer, ctx Context) error {
 	cd, ok := FindControlDefinition(n.Tag)
-	if !ok {
+	if !ok || cd.action == nil {
 		return fmt.Errorf("unimplemented tag: %s", n.Tag)
 	}
 	f := cd.action(*n)

chunks/render_test.go

@@ -22,65 +22,6 @@ var renderTests = []struct{ in, expected string }{
 	{"{{ar[1]}}", "second"},
 }
 
-var filterTests = []struct{ in, expected string }{
-	// Jekyll extensions
-	{`{{ obj | inspect }}`, `{"a":1}`},
-
-	// filters
-	// {{ product_price | default: 2.99 }}
-
-	// list filters
-	// {{ site.pages | map: 'category' | compact | join "," %}
-	// {% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}{{ my_array.first }}
-	{`{{"John, Paul, George, Ringo" | split: ", " | join: " and "}}`, "John and Paul and George and Ringo"},
-	{`{{ animals | sort | join: ", " }}`, "Sally Snake, giraffe, octopus, zebra"},
-	{`{{ sort_prop | sort: "weight" | inspect }}`, `[{"weight":null},{"weight":1},{"weight":3},{"weight":5}]`},
-
-	// last, map, slice, sort_natural, reverse, size, uniq
-
-	// string filters
-	// {{ "/my/fancy/url" | append: ".html" }}
-	// {% assign filename = "/index.html" %}{{ "website.com" | append: filename }}
-
-	// {{ "title" | capitalize }}
-	// {{ "my great title" | capitalize }}
-
-	// {{ "Parker Moore" | downcase }}
-
-	// {{ "Have you read 'James & the Giant Peach'?" | escape }}
-	// {{ "1 < 2 & 3" | escape_once }}
-	// {{ "1 &lt; 2 &amp; 3" | escape_once }}
-
-	// lstrip, newline_to_br, prepend, remove, remove_first, replace, replace_first
-	// rstrip, split, strip, strip_html, strip_newlines, truncate, truncatewords, upcase
-	// url_decode, url_encode
-
-	// number filters
-	// {{ -17 | abs }}
-	// {{ 4 | abs }}
-	// {{ "-19.86" | abs }}
-
-	// {{ 1.2 | ceil }}
-	// {{ 2.0 | ceil }}
-	// {{ 183.357 | ceil }}
-	// {{ "3.5" | ceil }}
-
-	// {{ 16 | divided_by: 4 }}
-	// {{ 5 | divided_by: 3 }}
-	// {{ 20 | divided_by: 7.0 }}
-
-	// {{ 1.2 | floor }}
-	// {{ 2.0 | floor }}
-	// {{ 183.357 | floor }}
-	// minus, modulo, plus, round,times
-
-	// date filters
-	// {{ article.published_at | date: "%a, %b %d, %y" }}
-	// {{ article.published_at | date: "%Y" }}
-	// {{ "March 14, 2016" | date: "%b %d, %y" }}
-	// {{ "now" | date: "%Y-%m-%d %H:%M" }
-}
-
 var renderTestContext = Context{map[string]interface{}{
 	"x": 123,
 	"obj": map[string]interface{}{
@@ -135,17 +76,3 @@ func TestRender(t *testing.T) {
 		})
 	}
 }
-
-func TestFilters(t *testing.T) {
-	for i, test := range filterTests {
-		t.Run(fmt.Sprintf("%02d", i), func(t *testing.T) {
-			tokens := Scan(test.in, "")
-			ast, err := Parse(tokens)
-			require.NoErrorf(t, err, test.in)
-			buf := new(bytes.Buffer)
-			err = ast.Render(buf, renderTestContext)
-			require.NoErrorf(t, err, test.in)
-			require.Equalf(t, test.expected, buf.String(), test.in)
-		})
-	}
-}

engine.go

@@ -9,8 +9,16 @@ import (
 	"io"
 
 	"github.com/osteele/liquid/chunks"
+	"github.com/osteele/liquid/filters"
+	"github.com/osteele/liquid/tags"
 )
 
+// TODO move the filters and tags from globals to the engine
+func init() {
+	tags.DefineStandardTags()
+	filters.DefineStandardFilters()
+}
+
 // Engine parses template source into renderable text.
 //
 // In the future, it will be configured with additional tags, filters, and the {%include%} search path.

expressions/filters.go

@@ -1,10 +1,8 @@
 package expressions
 
 import (
-	"encoding/json"
 	"fmt"
 	"reflect"
-	"strings"
 
 	"github.com/osteele/liquid/errors"
 	"github.com/osteele/liquid/generics"
@@ -16,53 +14,8 @@ func (e InterpreterError) Error() string { return string(e) }
 
 type valueFn func(Context) interface{}
 
-func joinFilter(in []interface{}, sep interface{}) interface{} {
-	a := make([]string, len(in))
-	s := ", "
-	if sep != nil {
-		s = fmt.Sprint(sep)
-	}
-	for i, x := range in {
-		a[i] = fmt.Sprint(x)
-	}
-	return strings.Join(a, s)
-}
-
-func sortFilter(in []interface{}, key interface{}) []interface{} {
-	out := make([]interface{}, len(in))
-	for i, v := range in {
-		out[i] = v
-	}
-	if key == nil {
-		generics.Sort(out)
-	} else {
-		generics.SortByProperty(out, key.(string))
-	}
-	return out
-}
-
-func splitFilter(in, sep string) interface{} {
-	return strings.Split(in, sep)
-}
-
 var filters = map[string]interface{}{}
 
-func init() {
-	DefineStandardFilters()
-}
-
-func DefineStandardFilters() {
-	// lists
-	DefineFilter("join", joinFilter)
-	DefineFilter("sort", sortFilter)
-
-	// strings
-	DefineFilter("split", splitFilter)
-
-	// Jekyll
-	DefineFilter("inspect", json.Marshal)
-}
-
 func DefineFilter(name string, fn interface{}) {
 	rf := reflect.ValueOf(fn)
 	switch {

filters/filter_test.go

@@ -0,0 +1,110 @@
+package filters
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/osteele/liquid/expressions"
+	"github.com/stretchr/testify/require"
+)
+
+func init() {
+	DefineStandardFilters()
+}
+
+var filterTests = []struct{ in, expected string }{
+	// Jekyll extensions
+	{`obj | inspect`, `{"a":1}`},
+
+	// filters
+	// product_price | default: 2.99 }}
+
+	// list filters
+	// site.pages | map: 'category' | compact | join "," %}
+	// {% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}my_array.first }}
+	{`"John, Paul, George, Ringo" | split: ", " | join: " and "`, "John and Paul and George and Ringo"},
+	{`animals | sort | join: ", "`, "Sally Snake, giraffe, octopus, zebra"},
+	{`sort_prop | sort: "weight" | inspect`, `[{"weight":null},{"weight":1},{"weight":3},{"weight":5}]`},
+
+	// last, map, slice, sort_natural, reverse, size, uniq
+
+	// string filters
+	// "/my/fancy/url" | append: ".html"
+	// {% assign filename = "/index.html" %}"website.com" | append: filename
+
+	// "title" | capitalize
+	// "my great title" | capitalize
+
+	// "Parker Moore" | downcase
+
+	// "Have you read 'James & the Giant Peach'?" | escape
+	// "1 < 2 & 3" | escape_once
+	// "1 &lt; 2 &amp; 3" | escape_once
+
+	// lstrip, newline_to_br, prepend, remove, remove_first, replace, replace_first
+	// rstrip, split, strip, strip_html, strip_newlines, truncate, truncatewords, upcase
+	// url_decode, url_encode
+
+	// number filters
+	// -17 | abs
+	// 4 | abs
+	// "-19.86" | abs
+
+	// 1.2 | ceil
+	// 2.0 | ceil
+	// 183.357 | ceil
+	// "3.5" | ceil
+
+	// 16 | divided_by: 4
+	// 5 | divided_by: 3
+	// 20 | divided_by: 7.0
+
+	// 1.2 | floor
+	// 2.0 | floor
+	// 183.357 | floor
+	// minus, modulo, plus, round,times
+
+	// date filters
+	// article.published_at | date: "%a, %b %d, %y"
+	// article.published_at | date: "%Y"
+	// "March 14, 2016" | date: "%b %d, %y"
+	// "now" | date: "%Y-%m-%d %H:%M" }
+}
+
+var filterTestContext = expressions.NewContext(map[string]interface{}{
+	"x": 123,
+	"obj": map[string]interface{}{
+		"a": 1,
+	},
+	"animals": []string{"zebra", "octopus", "giraffe", "Sally Snake"},
+	"pages": []map[string]interface{}{
+		{"category": "business"},
+		{"category": "celebrities"},
+		{},
+		{"category": "lifestyle"},
+		{"category": "sports"},
+		{},
+		{"category": "technology"},
+	},
+	"sort_prop": []map[string]interface{}{
+		{"weight": 1},
+		{"weight": 5},
+		{"weight": 3},
+		{"weight": nil},
+	},
+	"ar": []string{"first", "second", "third"},
+	"page": map[string]interface{}{
+		"title": "Introduction",
+	},
+})
+
+func TestFilters(t *testing.T) {
+	for i, test := range filterTests {
+		t.Run(fmt.Sprintf("%02d", i), func(t *testing.T) {
+			val, err := expressions.EvaluateExpr(test.in, filterTestContext)
+			require.NoErrorf(t, err, test.in)
+			actual := fmt.Sprintf("%s", val)
+			require.Equalf(t, test.expected, actual, test.in)
+		})
+	}
+}

filters/filters.go

@@ -0,0 +1,53 @@
+// The filters package defines the standard Liquid filters.
+package filters
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/osteele/liquid/expressions"
+	"github.com/osteele/liquid/generics"
+)
+
+// DefineStandardFilters defines the standard Liquid filters.
+func DefineStandardFilters() {
+	// lists
+	expressions.DefineFilter("join", joinFilter)
+	expressions.DefineFilter("sort", sortFilter)
+
+	// strings
+	expressions.DefineFilter("split", splitFilter)
+
+	// Jekyll
+	expressions.DefineFilter("inspect", json.Marshal)
+}
+
+func joinFilter(in []interface{}, sep interface{}) interface{} {
+	a := make([]string, len(in))
+	s := ", "
+	if sep != nil {
+		s = fmt.Sprint(sep)
+	}
+	for i, x := range in {
+		a[i] = fmt.Sprint(x)
+	}
+	return strings.Join(a, s)
+}
+
+func sortFilter(in []interface{}, key interface{}) []interface{} {
+	out := make([]interface{}, len(in))
+	for i, v := range in {
+		out[i] = v
+	}
+	if key == nil {
+		generics.Sort(out)
+	} else {
+		generics.SortByProperty(out, key.(string))
+	}
+	return out
+}
+
+func splitFilter(in, sep string) interface{} {
+	return strings.Split(in, sep)
+}

tags/tags.go

@@ -1,3 +1,4 @@
+// The tags package defines the standard Liquid tags.
 package tags
 
 import (
@@ -6,6 +7,7 @@ import (
 	"github.com/osteele/liquid/chunks"
 )
 
+// DefineStandardTags defines the standard Liquid tags.
 func DefineStandardTags() {
 	loopTags := []string{"break", "continue", "cycle"}
 	chunks.DefineControlTag("comment")
@@ -17,7 +19,6 @@ func DefineStandardTags() {
 	chunks.DefineControlTag("capture")
 }
 
-
 func ifTagAction(polarity bool) func(chunks.ASTControlTag) func(io.Writer, chunks.Context) error {
 	return func(node chunks.ASTControlTag) func(io.Writer, chunks.Context) error {
 		expr, err := chunks.MakeExpressionValueFn(node.Args)