Record source line number

chunks/chunk.go

@@ -15,6 +15,24 @@ type Chunk struct {
 	Source     string // Source is the entirety of the chunk, including the "{{", "{%", etc. markers.
 }
 
+// ChunkType is the type of a Chunk
+type ChunkType int
+
+const (
+	// TextChunkType is the type of a text Chunk
+	TextChunkType ChunkType = iota
+	// TagChunkType is the type of a tag Chunk "{%…%}"
+	TagChunkType
+	// ObjChunkType is the type of an object Chunk "{{…}}"
+	ObjChunkType
+)
+
+// SourceInfo contains a Chunk's source information
+type SourceInfo struct {
+	Pathname string
+	lineNo   int
+}
+
 func (c Chunk) String() string {
 	switch c.Type {
 	case TextChunkType:
@@ -28,20 +46,9 @@ func (c Chunk) String() string {
 	}
 }
 
-// SourceInfo contains a Chunk's source information
-type SourceInfo struct {
-	Pathname string
-	lineNo   int
+func (s SourceInfo) String() string {
+	if s.Pathname != "" {
+		return fmt.Sprintf("%s:%d", s.Pathname, s.lineNo)
+	}
+	return fmt.Sprintf("line %d", s.lineNo)
 }
-
-// ChunkType is the type of a Chunk
-type ChunkType int
-
-const (
-	// TextChunkType is the type of a text Chunk
-	TextChunkType ChunkType = iota
-	// TagChunkType is the type of a tag Chunk "{%…%}"
-	TagChunkType
-	// ObjChunkType is the type of an object Chunk "{{…}}"
-	ObjChunkType
-)

chunks/parser.go

@@ -8,23 +8,27 @@ import (
 
 // Parse creates an AST from a sequence of Chunks.
 func Parse(chunks []Chunk) (ASTNode, error) {
+	// a stack of control tag state, for matching nested {%if}{%endif%} etc.
 	type frame struct {
-		cd *controlTagDefinition
-		cn *ASTControlTag
-		ap *[]ASTNode
+		cd *controlTagDefinition // saved local ccd
+		cn *ASTControlTag        // saved local cn
+		ap *[]ASTNode            // saved local ap
 	}
 	var (
-		root      = &ASTSeq{}
-		ap        = &root.Children // pointer to current node accumulation slice
-		ccd       *controlTagDefinition
-		ccn       *ASTControlTag
-		stack     []frame // stack of control structures
-		rawTag    *ASTRaw
+		root      = &ASTSeq{}           // root of AST; will be returned
+		ap        = &root.Children      // newly-constructed nodes are appended here
+		ccd       *controlTagDefinition // current control tag definition
+		ccn       *ASTControlTag        // current control node
+		stack     []frame               // stack of control structures
+		rawTag    *ASTRaw               // current raw tag
 		inComment = false
 		inRaw     = false
 	)
 	for _, c := range chunks {
 		switch {
+		// The parser needs to know about comment and raw, because tags inside
+		// needn't match each other e.g. {%comment%}{%if%}{%endcomment%}
+		// TODO is this true?
 		case inComment:
 			if c.Type == TagChunkType && c.Name == "endcomment" {
 				inComment = false
@@ -84,7 +88,7 @@ func Parse(chunks []Chunk) (ASTNode, error) {
 		}
 	}
 	if ccd != nil {
-		return nil, fmt.Errorf("unterminated %s tag", ccd.name)
+		return nil, fmt.Errorf("unterminated %s tag at %s", ccd.name, ccn.SourceInfo)
 	}
 	if err := evaluateBuilders(root); err != nil {
 		return nil, err

chunks/scanner.go

@@ -4,6 +4,7 @@ package chunks
 
 import (
 	"regexp"
+	"strings"
 )
 
 var chunkMatcher = regexp.MustCompile(`{{\s*(.+?)\s*}}|{%\s*(\w+)(?:\s+((?:[^%]|%[^}])+?))?\s*%}`)
@@ -13,29 +14,30 @@ func Scan(data string, pathname string) []Chunk {
 	// TODO error on unterminated {{ and {%
 	// TODO probably an error when a tag contains a {{ or {%, at least outside of a string
 	var (
-		sourceInfo = SourceInfo{pathname, 0}
-		out        = make([]Chunk, 0)
-		p, pe      = 0, len(data)
-		matches    = chunkMatcher.FindAllStringSubmatchIndex(data, -1)
+		p, pe = 0, len(data)
+		si    = SourceInfo{pathname, 1}
+		out   = make([]Chunk, 0)
 	)
-	for _, m := range matches {
+	for _, m := range chunkMatcher.FindAllStringSubmatchIndex(data, -1) {
 		ts, te := m[0], m[1]
 		if p < ts {
-			out = append(out, Chunk{Type: TextChunkType, SourceInfo: sourceInfo, Source: data[p:ts]})
+			out = append(out, Chunk{Type: TextChunkType, SourceInfo: si, Source: data[p:ts]})
+			si.lineNo += strings.Count(data[p:ts], "\n")
 		}
+		source := data[ts:te]
 		switch data[ts+1] {
 		case '{':
 			out = append(out, Chunk{
 				Type:       ObjChunkType,
-				SourceInfo: sourceInfo,
-				Source:     data[ts:te],
+				SourceInfo: si,
+				Source:     source,
 				Parameters: data[m[2]:m[3]],
 			})
 		case '%':
 			c := Chunk{
 				Type:       TagChunkType,
-				SourceInfo: sourceInfo,
-				Source:     data[ts:te],
+				SourceInfo: si,
+				Source:     source,
 				Name:       data[m[4]:m[5]],
 			}
 			if m[6] > 0 {
@@ -43,10 +45,11 @@ func Scan(data string, pathname string) []Chunk {
 			}
 			out = append(out, c)
 		}
+		si.lineNo += strings.Count(source, "\n")
 		p = te
 	}
 	if p < pe {
-		out = append(out, Chunk{Type: TextChunkType, SourceInfo: sourceInfo, Source: data[p:]})
+		out = append(out, Chunk{Type: TextChunkType, SourceInfo: si, Source: data[p:]})
 	}
 	return out
 }