Merge pull request #7 from rudderlabs/fix.wrappingErrors

fix: wrapping errors for detecting custom errors

context.go

@@ -1,7 +1,6 @@
 package pongo2
 
 import (
-	"errors"
 	"fmt"
 	"regexp"
 )
@@ -108,8 +107,8 @@ func NewChildExecutionContext(parent *ExecutionContext) *ExecutionContext {
 	return newctx
 }
 
-func (ctx *ExecutionContext) Error(msg string, token *Token) *Error {
-	return ctx.OrigError(errors.New(msg), token)
+func (ctx *ExecutionContext) Error(err error, token *Token) *Error {
+	return ctx.OrigError(err, token)
 }
 
 func (ctx *ExecutionContext) OrigError(err error, token *Token) *Error {

filters.go

@@ -104,7 +104,7 @@ func (p *Parser) parseFilter() (*filterCall, *Error) {
 
 	// Check filter ident
 	if identToken == nil {
-		return nil, p.Error("Filter name must be an identifier.", nil)
+		return nil, p.Error(fmt.Errorf("Filter name must be an identifier."), nil)
 	}
 
 	filter := &filterCall{
@@ -115,15 +115,15 @@ func (p *Parser) parseFilter() (*filterCall, *Error) {
 	// Get the appropriate filter function and bind it
 	filterFn, exists := filters[identToken.Val]
 	if !exists {
-		return nil, p.Error(fmt.Sprintf("Filter '%s' does not exist.", identToken.Val), identToken)
+		return nil, p.Error(fmt.Errorf("Filter '%s' does not exist.", identToken.Val), identToken)
 	}
 
 	filter.filterFunc = filterFn
 
 	// Check for filter-argument (2 tokens needed: ':' ARG)
 	if p.Match(TokenSymbol, ":") != nil {
 		if p.Peek(TokenSymbol, "}}") != nil {
-			return nil, p.Error("Filter parameter required after ':'.", nil)
+			return nil, p.Error(fmt.Errorf("Filter parameter required after ':'."), nil)
 		}
 
 		// Get filter argument expression

parser.go

@@ -1,7 +1,6 @@
 package pongo2
 
 import (
-	"errors"
 	"fmt"
 	"strings"
 )
@@ -179,7 +178,7 @@ func (p *Parser) GetR(shift int) *Token {
 // The 'token'-argument is optional. If provided, it will take
 // the token's position information. If not provided, it will
 // automatically use the CURRENT token's position information.
-func (p *Parser) Error(msg string, token *Token) *Error {
+func (p *Parser) Error(err error, token *Token) *Error {
 	if token == nil {
 		// Set current token
 		token = p.Current()
@@ -202,7 +201,7 @@ func (p *Parser) Error(msg string, token *Token) *Error {
 		Line:      line,
 		Column:    col,
 		Token:     token,
-		OrigError: errors.New(msg),
+		OrigError: err,
 	}
 }
 
@@ -244,7 +243,7 @@ func (p *Parser) WrapUntilTag(names ...string) (*NodeWrapper, *Parser, *Error) {
 						t := p.Current()
 						p.Consume()
 						if t == nil {
-							return nil, nil, p.Error("Unexpected EOF.", p.lastToken)
+							return nil, nil, p.Error(fmt.Errorf("Unexpected EOF."), p.lastToken)
 						}
 						tagArgs = append(tagArgs, t)
 					}
@@ -261,7 +260,7 @@ func (p *Parser) WrapUntilTag(names ...string) (*NodeWrapper, *Parser, *Error) {
 		wrapper.nodes = append(wrapper.nodes, node)
 	}
 
-	return nil, nil, p.Error(fmt.Sprintf("Unexpected EOF, expected tag %s.", strings.Join(names, " or ")),
+	return nil, nil, p.Error(fmt.Errorf("Unexpected EOF, expected tag %s.", strings.Join(names, " or ")),
 		p.lastToken)
 }
 
@@ -298,7 +297,7 @@ func (p *Parser) SkipUntilTag(names ...string) *Error {
 						p.Consume()
 						if p.Current() == nil {
 							// EOF encountered
-							return p.Error("Unexpected EOF, expected '%}'", p.lastToken)
+							return p.Error(fmt.Errorf("Unexpected EOF, expected '%%}'"), p.lastToken)
 						}
 					}
 				}
@@ -307,9 +306,9 @@ func (p *Parser) SkipUntilTag(names ...string) *Error {
 		t := p.Current()
 		p.Consume()
 		if t == nil {
-			return p.Error("Unexpected EOF.", p.lastToken)
+			return p.Error(fmt.Errorf("Unexpected EOF."), p.lastToken)
 		}
 	}
 
-	return p.Error(fmt.Sprintf("Unexpected EOF, expected tag %s.", strings.Join(names, " or ")), p.lastToken)
+	return p.Error(fmt.Errorf("Unexpected EOF, expected tag %s.", strings.Join(names, " or ")), p.lastToken)
 }

parser_document.go

@@ -1,5 +1,7 @@
 package pongo2
 
+import "fmt"
+
 // Doc = { ( Filter | Tag | HTML ) }
 func (p *Parser) parseDocElement() (INode, *Error) {
 	t := p.Current()
@@ -31,7 +33,7 @@ func (p *Parser) parseDocElement() (INode, *Error) {
 			return tag, nil
 		}
 	}
-	return nil, p.Error("Unexpected token (only HTML/tags/filters in templates allowed)", t)
+	return nil, p.Error(fmt.Errorf("Unexpected token (only HTML/tags/filters in templates allowed)"), t)
 }
 
 func (tpl *Template) parse() *Error {

parser_expression.go

@@ -158,7 +158,7 @@ func (expr *Expression) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 				return AsValue(v2.IsTrue()), nil
 			}
 		default:
-			return nil, ctx.Error(fmt.Sprintf("unimplemented: %s", expr.opToken.Val), expr.opToken)
+			return nil, ctx.Error(fmt.Errorf("unimplemented: %s", expr.opToken.Val), expr.opToken)
 		}
 	} else {
 		return v1, nil
@@ -217,7 +217,7 @@ func (expr *relationalExpression) Evaluate(ctx *ExecutionContext) (*Value, *Erro
 		case "in":
 			return AsValue(v2.Contains(v1)), nil
 		default:
-			return nil, ctx.Error(fmt.Sprintf("unimplemented: %s", expr.opToken.Val), expr.opToken)
+			return nil, ctx.Error(fmt.Errorf("unimplemented: %s", expr.opToken.Val), expr.opToken)
 		}
 	} else {
 		return v1, nil
@@ -243,10 +243,10 @@ func (expr *simpleExpression) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 			case result.IsInteger():
 				result = AsValue(-1 * result.Integer())
 			default:
-				return nil, ctx.Error("Operation between a number and a non-(float/integer) is not possible", nil)
+				return nil, ctx.Error(fmt.Errorf("Operation between a number and a non-(float/integer) is not possible"), nil)
 			}
 		} else {
-			return nil, ctx.Error("Negative sign on a non-number expression", expr.GetPositionToken())
+			return nil, ctx.Error(fmt.Errorf("Negative sign on a non-number expression"), expr.GetPositionToken())
 		}
 	}
 
@@ -275,7 +275,7 @@ func (expr *simpleExpression) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 			// Result will be an integer
 			return AsValue(result.Integer() - t2.Integer()), nil
 		default:
-			return nil, ctx.Error("Unimplemented", expr.GetPositionToken())
+			return nil, ctx.Error(fmt.Errorf("Unimplemented"), expr.GetPositionToken())
 		}
 	}
 
@@ -305,25 +305,25 @@ func (expr *term) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 				// Result will be float
 				divisor := f2.Float()
 				if divisor == 0 {
-					return nil, ctx.Error("float divide by zero", expr.factor2.GetPositionToken())
+					return nil, ctx.Error(fmt.Errorf("float divide by zero"), expr.factor2.GetPositionToken())
 				}
 				return AsValue(f1.Float() / divisor), nil
 			}
 			// Result will be int
 			divisor := f2.Integer()
 			if divisor == 0 {
-				return nil, ctx.Error("integer divide by zero", expr.factor2.GetPositionToken())
+				return nil, ctx.Error(fmt.Errorf("integer divide by zero"), expr.factor2.GetPositionToken())
 			}
 			return AsValue(f1.Integer() / divisor), nil
 		case "%":
 			// Result will be int
 			divisor := f2.Integer()
 			if divisor == 0 {
-				return nil, ctx.Error("integer divide by zero", expr.factor2.GetPositionToken())
+				return nil, ctx.Error(fmt.Errorf("integer divide by zero"), expr.factor2.GetPositionToken())
 			}
 			return AsValue(f1.Integer() % divisor), nil
 		default:
-			return nil, ctx.Error("unimplemented", expr.opToken)
+			return nil, ctx.Error(fmt.Errorf("unimplemented"), expr.opToken)
 		}
 	} else {
 		return f1, nil
@@ -352,7 +352,7 @@ func (p *Parser) parseFactor() (IEvaluator, *Error) {
 			return nil, err
 		}
 		if p.Match(TokenSymbol, ")") == nil {
-			return nil, p.Error("Closing bracket expected after expression", nil)
+			return nil, p.Error(fmt.Errorf("Closing bracket expected after expression"), nil)
 		}
 		return expr, nil
 	}

tags.go

@@ -89,19 +89,19 @@ func (p *Parser) parseTagElement() (INodeTag, *Error) {
 
 	// Check for identifier
 	if tokenName == nil {
-		return nil, p.Error("Tag name must be an identifier.", nil)
+		return nil, p.Error(fmt.Errorf("Tag name must be an identifier."), nil)
 	}
 
 	// Check for the existing tag
 	tag, exists := tags[tokenName.Val]
 	if !exists {
 		// Does not exists
-		return nil, p.Error(fmt.Sprintf("Tag '%s' not found (or beginning tag not provided)", tokenName.Val), tokenName)
+		return nil, p.Error(fmt.Errorf("Tag '%s' not found (or beginning tag not provided)", tokenName.Val), tokenName)
 	}
 
 	// Check sandbox tag restriction
 	if _, isBanned := p.template.set.bannedTags[tokenName.Val]; isBanned {
-		return nil, p.Error(fmt.Sprintf("Usage of tag '%s' is not allowed (sandbox restriction active).", tokenName.Val), tokenName)
+		return nil, p.Error(fmt.Errorf("Usage of tag '%s' is not allowed (sandbox restriction active).", tokenName.Val), tokenName)
 	}
 
 	var argsToken []*Token
@@ -113,7 +113,7 @@ func (p *Parser) parseTagElement() (INodeTag, *Error) {
 
 	// EOF?
 	if p.Remaining() == 0 {
-		return nil, p.Error("Unexpectedly reached EOF, no tag end found.", p.lastToken)
+		return nil, p.Error(fmt.Errorf("Unexpectedly reached EOF, no tag end found."), p.lastToken)
 	}
 
 	p.Match(TokenSymbol, "%}")

tags_autoescape.go

@@ -1,5 +1,7 @@
 package pongo2
 
+import "fmt"
+
 type tagAutoescapeNode struct {
 	wrapper    *NodeWrapper
 	autoescape bool
@@ -30,18 +32,18 @@ func tagAutoescapeParser(doc *Parser, start *Token, arguments *Parser) (INodeTag
 
 	modeToken := arguments.MatchType(TokenIdentifier)
 	if modeToken == nil {
-		return nil, arguments.Error("A mode is required for autoescape-tag.", nil)
+		return nil, arguments.Error(fmt.Errorf("A mode is required for autoescape-tag."), nil)
 	}
 	if modeToken.Val == "on" {
 		autoescapeNode.autoescape = true
 	} else if modeToken.Val == "off" {
 		autoescapeNode.autoescape = false
 	} else {
-		return nil, arguments.Error("Only 'on' or 'off' is valid as an autoescape-mode.", nil)
+		return nil, arguments.Error(fmt.Errorf("Only 'on' or 'off' is valid as an autoescape-mode."), nil)
 	}
 
 	if arguments.Remaining() > 0 {
-		return nil, arguments.Error("Malformed autoescape-tag arguments.", nil)
+		return nil, arguments.Error(fmt.Errorf("Malformed autoescape-tag arguments."), nil)
 	}
 
 	return autoescapeNode, nil

tags_block.go

@@ -35,7 +35,7 @@ func (node *tagBlockNode) Execute(ctx *ExecutionContext, writer TemplateWriter)
 	lenBlockWrappers := len(blockWrappers)
 
 	if lenBlockWrappers == 0 {
-		return ctx.Error("internal error: len(block_wrappers) == 0 in tagBlockNode.Execute()", nil)
+		return ctx.Error(fmt.Errorf("internal error: len(block_wrappers) == 0 in tagBlockNode.Execute()"), nil)
 	}
 
 	blockWrapper := blockWrappers[lenBlockWrappers-1]
@@ -80,16 +80,16 @@ func (t tagBlockInformation) Super() (*Value, error) {
 
 func tagBlockParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
 	if arguments.Count() == 0 {
-		return nil, arguments.Error("Tag 'block' requires an identifier.", nil)
+		return nil, arguments.Error(fmt.Errorf("Tag 'block' requires an identifier."), nil)
 	}
 
 	nameToken := arguments.MatchType(TokenIdentifier)
 	if nameToken == nil {
-		return nil, arguments.Error("First argument for tag 'block' must be an identifier.", nil)
+		return nil, arguments.Error(fmt.Errorf("First argument for tag 'block' must be an identifier."), nil)
 	}
 
 	if arguments.Remaining() != 0 {
-		return nil, arguments.Error("Tag 'block' takes exactly 1 argument (an identifier).", nil)
+		return nil, arguments.Error(fmt.Errorf("Tag 'block' takes exactly 1 argument (an identifier)."), nil)
 	}
 
 	wrapper, endtagargs, err := doc.WrapUntilTag("endblock")
@@ -100,13 +100,13 @@ func tagBlockParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 		endtagnameToken := endtagargs.MatchType(TokenIdentifier)
 		if endtagnameToken != nil {
 			if endtagnameToken.Val != nameToken.Val {
-				return nil, endtagargs.Error(fmt.Sprintf("Name for 'endblock' must equal to 'block'-tag's name ('%s' != '%s').",
+				return nil, endtagargs.Error(fmt.Errorf("Name for 'endblock' must equal to 'block'-tag's name ('%s' != '%s').",
 					nameToken.Val, endtagnameToken.Val), nil)
 			}
 		}
 
 		if endtagnameToken == nil || endtagargs.Remaining() > 0 {
-			return nil, endtagargs.Error("Either no or only one argument (identifier) allowed for 'endblock'.", nil)
+			return nil, endtagargs.Error(fmt.Errorf("Either no or only one argument (identifier) allowed for 'endblock'."), nil)
 		}
 	}
 
@@ -118,7 +118,7 @@ func tagBlockParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 	if !hasBlock {
 		tpl.blocks[nameToken.Val] = wrapper
 	} else {
-		return nil, arguments.Error(fmt.Sprintf("Block named '%s' already defined", nameToken.Val), nil)
+		return nil, arguments.Error(fmt.Errorf("Block named '%s' already defined", nameToken.Val), nil)
 	}
 
 	return &tagBlockNode{name: nameToken.Val}, nil

tags_comment.go

@@ -1,5 +1,7 @@
 package pongo2
 
+import "fmt"
+
 type tagCommentNode struct{}
 
 func (node *tagCommentNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
@@ -16,7 +18,7 @@ func tagCommentParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *
 	}
 
 	if arguments.Count() != 0 {
-		return nil, arguments.Error("Tag 'comment' does not take any argument.", nil)
+		return nil, arguments.Error(fmt.Errorf("Tag 'comment' does not take any argument."), nil)
 	}
 
 	return commentNode, nil

tags_cycle.go

@@ -1,5 +1,7 @@
 package pongo2
 
+import "fmt"
+
 type tagCycleValue struct {
 	node  *tagCycleNode
 	value *Value
@@ -81,7 +83,7 @@ func tagCycleParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 
 			nameToken := arguments.MatchType(TokenIdentifier)
 			if nameToken == nil {
-				return nil, arguments.Error("Name (identifier) expected after 'as'.", nil)
+				return nil, arguments.Error(fmt.Errorf("Name (identifier) expected after 'as'."), nil)
 			}
 			cycleNode.asName = nameToken.Val
 
@@ -95,7 +97,7 @@ func tagCycleParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 	}
 
 	if arguments.Remaining() > 0 {
-		return nil, arguments.Error("Malformed cycle-tag.", nil)
+		return nil, arguments.Error(fmt.Errorf("Malformed cycle-tag."), nil)
 	}
 
 	return cycleNode, nil