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Remove the outdated skipStmt method (#345)
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@vladmos
vladmos authored Jul 30, 2018
1 parent 651ea75 commit 4a7914a
Showing 1 changed file with 8 additions and 112 deletions.
120 changes: 8 additions & 112 deletions build/lex.go
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Original file line number Diff line number Diff line change
Expand Up @@ -28,11 +28,11 @@ import (

// BuildFilenames is a collection of filenames in lowercase that are treated as BUILD files.
var BuildFilenames = map[string]bool{
"build": true,
"build.bazel": true,
"workspace": true,
"build": true,
"build.bazel": true,
"workspace": true,
"workspace.bazel": true,
"stdin": true,
"stdin": true,
}

// ParseBuild parses a file, marks it as a BUILD file and returns the corresponding parse tree.
Expand Down Expand Up @@ -82,7 +82,6 @@ type input struct {
pos Position // current input position
lineComments []Comment // accumulated line comments
suffixComments []Comment // accumulated suffix comments
endStmt int // position of the end of the current statement
depth int // nesting of [ ] { } ( )
cleanLine bool // true if the current line only contains whitespace before the current position
indent int // current line indentation in spaces
Expand Down Expand Up @@ -110,7 +109,6 @@ func newInput(filename string, data []byte) *input {
pos: Position{Line: 1, LineRune: 1, Byte: 0},
cleanLine: true,
indents: []int{0},
endStmt: -1, // -1 denotes it's not inside a statement
}
}

Expand Down Expand Up @@ -224,25 +222,6 @@ func (in *input) Lex(val *yySymType) int {
// Skip past spaces, stopping at non-space or EOF.
countNL := 0 // number of newlines we've skipped past
for !in.eof() {
// If a single statement is split into multiple lines, we don't need
// to track indentations and unindentations within these lines. For example:
//
// def f(
// # This indentation should be ignored
// x):
// # This unindentation should be ignored
// # Actual indentation is from 0 to 2 spaces here
// return x
//
// To handle this case, when we reach the beginning of a statement we scan forward to see where
// it should end and record the number of input bytes remaining at that endpoint.
//
// If --format_bzl is set to false, top level blocks (e.g. an entire function definition)
// is considered as a single statement.
if in.endStmt != -1 && len(in.remaining) == in.endStmt {
in.endStmt = -1
}

// Skip over spaces. Count newlines so we can give the parser
// information about where top-level blank lines are,
// for top-level comment assignment.
Expand All @@ -251,7 +230,7 @@ func (in *input) Lex(val *yySymType) int {
if c == '\n' {
in.indent = 0
in.cleanLine = true
if in.endStmt == -1 {
if in.depth == 0 {
// Not in a statememt. Tell parser about top-level blank line.
in.startToken(val)
in.readRune()
Expand All @@ -271,6 +250,7 @@ func (in *input) Lex(val *yySymType) int {
// If a line contains just a comment its indentation level doesn't matter.
// Reset it to zero.
in.indent = 0
isLineComment := in.cleanLine
in.cleanLine = true

// Is this comment the only thing on its line?
Expand Down Expand Up @@ -307,7 +287,7 @@ func (in *input) Lex(val *yySymType) int {
// If we are at top level (not in a rule), hand the comment to
// the parser as a _COMMENT token. The grammar is written
// to handle top-level comments itself.
if in.endStmt == -1 {
if in.depth == 0 && isLineComment {
// Not in a statement. Tell parser about top-level comment.
return _COMMENT
}
Expand Down Expand Up @@ -339,7 +319,7 @@ func (in *input) Lex(val *yySymType) int {
// Check for changes in indentation
// Skip if we're inside a statement, or if there were non-space
// characters before in the current line.
if in.endStmt == -1 && in.cleanLine {
if in.depth == 0 && in.cleanLine {
if in.indent > in.currentIndent() {
// A new indentation block starts
in.indents = append(in.indents, in.indent)
Expand Down Expand Up @@ -381,11 +361,6 @@ func (in *input) Lex(val *yySymType) int {
return _EOF
}

// If endStmt is 0, we need to recompute where the end of the next statement is.
if in.endStmt == -1 {
in.endStmt = len(in.skipStmt(in.remaining))
}

// Punctuation tokens.
switch c := in.peekRune(); c {
case '[', '(', '{':
Expand Down Expand Up @@ -554,85 +529,6 @@ var keywordToken = map[string]int{
"return": _RETURN,
}

// Python scanning.
// About 1% of BUILD files embed arbitrary Python into the file.
// We do not attempt to parse it. Instead, we lex just enough to scan
// beyond it, treating the Python block as an unintepreted blob.

// skipStmt returns the data remaining after the statement beginning at p.
// It does not advance the input position.
// (The only reason for the input receiver is to be able to call in.Error.)
func (in *input) skipStmt(p []byte) []byte {
quote := byte(0) // if non-zero, the kind of quote we're in
tripleQuote := false // if true, the quote is a triple quote
depth := 0 // nesting depth for ( ) [ ] { }
var rest []byte // data after the Python block

defer func() {
if quote != 0 {
in.Error("EOF scanning Python quoted string")
}
}()

// Scan over input one byte at a time until we find
// an unindented, non-blank, non-comment line
// outside quoted strings and brackets.
for i := 0; i < len(p); i++ {
c := p[i]
if quote != 0 && c == quote && !tripleQuote {
quote = 0
continue
}
if quote != 0 && c == quote && tripleQuote && i+2 < len(p) && p[i+1] == quote && p[i+2] == quote {
i += 2
quote = 0
tripleQuote = false
continue
}
if quote != 0 {
if c == '\\' {
i++ // skip escaped char
}
continue
}
if c == '\'' || c == '"' {
if i+2 < len(p) && p[i+1] == c && p[i+2] == c {
quote = c
tripleQuote = true
i += 2
continue
}
quote = c
continue
}

if depth == 0 && i > 0 && p[i] == '\n' && p[i-1] != '\\' {
// Possible stopping point. Save the earliest one we find.
if rest == nil {
rest = p[i:]
}
return rest
}

switch c {
case '#':
// Skip comment.
for i < len(p) && p[i] != '\n' {
i++
}
// Rewind 1 position back because \n should be handled at the next iteration
i--

case '(', '[', '{':
depth++

case ')', ']', '}':
depth--
}
}
return rest
}

// Comment assignment.
// We build two lists of all subexpressions, preorder and postorder.
// The preorder list is ordered by start location, with outer expressions first.
Expand Down

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