blob: ae8805856cd6aa30a0536ed95ecae3ba6381b38e [file] [log] [blame]
package hclsyntax
import (
"fmt"
"strings"
"unicode"
"github.com/apparentlymart/go-textseg/v13/textseg"
"github.com/hashicorp/hcl/v2"
"github.com/zclconf/go-cty/cty"
)
func (p *parser) ParseTemplate() (Expression, hcl.Diagnostics) {
return p.parseTemplate(TokenEOF, false)
}
func (p *parser) parseTemplate(end TokenType, flushHeredoc bool) (Expression, hcl.Diagnostics) {
exprs, passthru, rng, diags := p.parseTemplateInner(end, flushHeredoc)
if passthru {
if len(exprs) != 1 {
panic("passthru set with len(exprs) != 1")
}
return &TemplateWrapExpr{
Wrapped: exprs[0],
SrcRange: rng,
}, diags
}
return &TemplateExpr{
Parts: exprs,
SrcRange: rng,
}, diags
}
func (p *parser) parseTemplateInner(end TokenType, flushHeredoc bool) ([]Expression, bool, hcl.Range, hcl.Diagnostics) {
parts, diags := p.parseTemplateParts(end)
if flushHeredoc {
flushHeredocTemplateParts(parts) // Trim off leading spaces on lines per the flush heredoc spec
}
tp := templateParser{
Tokens: parts.Tokens,
SrcRange: parts.SrcRange,
}
exprs, exprsDiags := tp.parseRoot()
diags = append(diags, exprsDiags...)
passthru := false
if len(parts.Tokens) == 2 { // one real token and one synthetic "end" token
if _, isInterp := parts.Tokens[0].(*templateInterpToken); isInterp {
passthru = true
}
}
return exprs, passthru, parts.SrcRange, diags
}
type templateParser struct {
Tokens []templateToken
SrcRange hcl.Range
pos int
}
func (p *templateParser) parseRoot() ([]Expression, hcl.Diagnostics) {
var exprs []Expression
var diags hcl.Diagnostics
for {
next := p.Peek()
if _, isEnd := next.(*templateEndToken); isEnd {
break
}
expr, exprDiags := p.parseExpr()
diags = append(diags, exprDiags...)
exprs = append(exprs, expr)
}
return exprs, diags
}
func (p *templateParser) parseExpr() (Expression, hcl.Diagnostics) {
next := p.Peek()
switch tok := next.(type) {
case *templateLiteralToken:
p.Read() // eat literal
return &LiteralValueExpr{
Val: cty.StringVal(tok.Val),
SrcRange: tok.SrcRange,
}, nil
case *templateInterpToken:
p.Read() // eat interp
return tok.Expr, nil
case *templateIfToken:
return p.parseIf()
case *templateForToken:
return p.parseFor()
case *templateEndToken:
p.Read() // eat erroneous token
return errPlaceholderExpr(tok.SrcRange), hcl.Diagnostics{
{
// This is a particularly unhelpful diagnostic, so callers
// should attempt to pre-empt it and produce a more helpful
// diagnostic that is context-aware.
Severity: hcl.DiagError,
Summary: "Unexpected end of template",
Detail: "The control directives within this template are unbalanced.",
Subject: &tok.SrcRange,
},
}
case *templateEndCtrlToken:
p.Read() // eat erroneous token
return errPlaceholderExpr(tok.SrcRange), hcl.Diagnostics{
{
Severity: hcl.DiagError,
Summary: fmt.Sprintf("Unexpected %s directive", tok.Name()),
Detail: "The control directives within this template are unbalanced.",
Subject: &tok.SrcRange,
},
}
default:
// should never happen, because above should be exhaustive
panic(fmt.Sprintf("unhandled template token type %T", next))
}
}
func (p *templateParser) parseIf() (Expression, hcl.Diagnostics) {
open := p.Read()
openIf, isIf := open.(*templateIfToken)
if !isIf {
// should never happen if caller is behaving
panic("parseIf called with peeker not pointing at if token")
}
var ifExprs, elseExprs []Expression
var diags hcl.Diagnostics
var endifRange hcl.Range
currentExprs := &ifExprs
Token:
for {
next := p.Peek()
if end, isEnd := next.(*templateEndToken); isEnd {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Unexpected end of template",
Detail: fmt.Sprintf(
"The if directive at %s is missing its corresponding endif directive.",
openIf.SrcRange,
),
Subject: &end.SrcRange,
})
return errPlaceholderExpr(end.SrcRange), diags
}
if end, isCtrlEnd := next.(*templateEndCtrlToken); isCtrlEnd {
p.Read() // eat end directive
switch end.Type {
case templateElse:
if currentExprs == &ifExprs {
currentExprs = &elseExprs
continue Token
}
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Unexpected else directive",
Detail: fmt.Sprintf(
"Already in the else clause for the if started at %s.",
openIf.SrcRange,
),
Subject: &end.SrcRange,
})
case templateEndIf:
endifRange = end.SrcRange
break Token
default:
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: fmt.Sprintf("Unexpected %s directive", end.Name()),
Detail: fmt.Sprintf(
"Expecting an endif directive for the if started at %s.",
openIf.SrcRange,
),
Subject: &end.SrcRange,
})
}
return errPlaceholderExpr(end.SrcRange), diags
}
expr, exprDiags := p.parseExpr()
diags = append(diags, exprDiags...)
*currentExprs = append(*currentExprs, expr)
}
if len(ifExprs) == 0 {
ifExprs = append(ifExprs, &LiteralValueExpr{
Val: cty.StringVal(""),
SrcRange: hcl.Range{
Filename: openIf.SrcRange.Filename,
Start: openIf.SrcRange.End,
End: openIf.SrcRange.End,
},
})
}
if len(elseExprs) == 0 {
elseExprs = append(elseExprs, &LiteralValueExpr{
Val: cty.StringVal(""),
SrcRange: hcl.Range{
Filename: endifRange.Filename,
Start: endifRange.Start,
End: endifRange.Start,
},
})
}
trueExpr := &TemplateExpr{
Parts: ifExprs,
SrcRange: hcl.RangeBetween(ifExprs[0].Range(), ifExprs[len(ifExprs)-1].Range()),
}
falseExpr := &TemplateExpr{
Parts: elseExprs,
SrcRange: hcl.RangeBetween(elseExprs[0].Range(), elseExprs[len(elseExprs)-1].Range()),
}
return &ConditionalExpr{
Condition: openIf.CondExpr,
TrueResult: trueExpr,
FalseResult: falseExpr,
SrcRange: hcl.RangeBetween(openIf.SrcRange, endifRange),
}, diags
}
func (p *templateParser) parseFor() (Expression, hcl.Diagnostics) {
open := p.Read()
openFor, isFor := open.(*templateForToken)
if !isFor {
// should never happen if caller is behaving
panic("parseFor called with peeker not pointing at for token")
}
var contentExprs []Expression
var diags hcl.Diagnostics
var endforRange hcl.Range
Token:
for {
next := p.Peek()
if end, isEnd := next.(*templateEndToken); isEnd {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Unexpected end of template",
Detail: fmt.Sprintf(
"The for directive at %s is missing its corresponding endfor directive.",
openFor.SrcRange,
),
Subject: &end.SrcRange,
})
return errPlaceholderExpr(end.SrcRange), diags
}
if end, isCtrlEnd := next.(*templateEndCtrlToken); isCtrlEnd {
p.Read() // eat end directive
switch end.Type {
case templateElse:
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Unexpected else directive",
Detail: "An else clause is not expected for a for directive.",
Subject: &end.SrcRange,
})
case templateEndFor:
endforRange = end.SrcRange
break Token
default:
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: fmt.Sprintf("Unexpected %s directive", end.Name()),
Detail: fmt.Sprintf(
"Expecting an endfor directive corresponding to the for directive at %s.",
openFor.SrcRange,
),
Subject: &end.SrcRange,
})
}
return errPlaceholderExpr(end.SrcRange), diags
}
expr, exprDiags := p.parseExpr()
diags = append(diags, exprDiags...)
contentExprs = append(contentExprs, expr)
}
if len(contentExprs) == 0 {
contentExprs = append(contentExprs, &LiteralValueExpr{
Val: cty.StringVal(""),
SrcRange: hcl.Range{
Filename: openFor.SrcRange.Filename,
Start: openFor.SrcRange.End,
End: openFor.SrcRange.End,
},
})
}
contentExpr := &TemplateExpr{
Parts: contentExprs,
SrcRange: hcl.RangeBetween(contentExprs[0].Range(), contentExprs[len(contentExprs)-1].Range()),
}
forExpr := &ForExpr{
KeyVar: openFor.KeyVar,
ValVar: openFor.ValVar,
CollExpr: openFor.CollExpr,
ValExpr: contentExpr,
SrcRange: hcl.RangeBetween(openFor.SrcRange, endforRange),
OpenRange: openFor.SrcRange,
CloseRange: endforRange,
}
return &TemplateJoinExpr{
Tuple: forExpr,
}, diags
}
func (p *templateParser) Peek() templateToken {
return p.Tokens[p.pos]
}
func (p *templateParser) Read() templateToken {
ret := p.Peek()
if _, end := ret.(*templateEndToken); !end {
p.pos++
}
return ret
}
// parseTemplateParts produces a flat sequence of "template tokens", which are
// either literal values (with any "trimming" already applied), interpolation
// sequences, or control flow markers.
//
// A further pass is required on the result to turn it into an AST.
func (p *parser) parseTemplateParts(end TokenType) (*templateParts, hcl.Diagnostics) {
var parts []templateToken
var diags hcl.Diagnostics
startRange := p.NextRange()
ltrimNext := false
nextCanTrimPrev := false
var endRange hcl.Range
Token:
for {
next := p.Read()
if next.Type == end {
// all done!
endRange = next.Range
break
}
ltrim := ltrimNext
ltrimNext = false
canTrimPrev := nextCanTrimPrev
nextCanTrimPrev = false
switch next.Type {
case TokenStringLit, TokenQuotedLit:
str, strDiags := ParseStringLiteralToken(next)
diags = append(diags, strDiags...)
if ltrim {
str = strings.TrimLeftFunc(str, unicode.IsSpace)
}
parts = append(parts, &templateLiteralToken{
Val: str,
SrcRange: next.Range,
})
nextCanTrimPrev = true
case TokenTemplateInterp:
// if the opener is ${~ then we want to eat any trailing whitespace
// in the preceding literal token, assuming it is indeed a literal
// token.
if canTrimPrev && len(next.Bytes) == 3 && next.Bytes[2] == '~' && len(parts) > 0 {
prevExpr := parts[len(parts)-1]
if lexpr, ok := prevExpr.(*templateLiteralToken); ok {
lexpr.Val = strings.TrimRightFunc(lexpr.Val, unicode.IsSpace)
}
}
p.PushIncludeNewlines(false)
expr, exprDiags := p.ParseExpression()
diags = append(diags, exprDiags...)
close := p.Peek()
if close.Type != TokenTemplateSeqEnd {
if !p.recovery {
switch close.Type {
case TokenEOF:
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Unclosed template interpolation sequence",
Detail: "There is no closing brace for this interpolation sequence before the end of the file. This might be caused by incorrect nesting inside the given expression.",
Subject: &startRange,
})
case TokenColon:
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Extra characters after interpolation expression",
Detail: "Template interpolation doesn't expect a colon at this location. Did you intend this to be a literal sequence to be processed as part of another language? If so, you can escape it by starting with \"$${\" instead of just \"${\".",
Subject: &close.Range,
Context: hcl.RangeBetween(startRange, close.Range).Ptr(),
})
default:
if (close.Type == TokenCQuote || close.Type == TokenOQuote) && end == TokenCQuote {
// We'll get here if we're processing a _quoted_
// template and we find an errant quote inside an
// interpolation sequence, which suggests that
// the interpolation sequence is missing its terminator.
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Unclosed template interpolation sequence",
Detail: "There is no closing brace for this interpolation sequence before the end of the quoted template. This might be caused by incorrect nesting inside the given expression.",
Subject: &startRange,
})
} else {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Extra characters after interpolation expression",
Detail: "Expected a closing brace to end the interpolation expression, but found extra characters.\n\nThis can happen when you include interpolation syntax for another language, such as shell scripting, but forget to escape the interpolation start token. If this is an embedded sequence for another language, escape it by starting with \"$${\" instead of just \"${\".",
Subject: &close.Range,
Context: hcl.RangeBetween(startRange, close.Range).Ptr(),
})
}
}
}
p.recover(TokenTemplateSeqEnd)
} else {
p.Read() // eat closing brace
// If the closer is ~} then we want to eat any leading
// whitespace on the next token, if it turns out to be a
// literal token.
if len(close.Bytes) == 2 && close.Bytes[0] == '~' {
ltrimNext = true
}
}
p.PopIncludeNewlines()
parts = append(parts, &templateInterpToken{
Expr: expr,
SrcRange: hcl.RangeBetween(next.Range, close.Range),
})
case TokenTemplateControl:
// if the opener is %{~ then we want to eat any trailing whitespace
// in the preceding literal token, assuming it is indeed a literal
// token.
if canTrimPrev && len(next.Bytes) == 3 && next.Bytes[2] == '~' && len(parts) > 0 {
prevExpr := parts[len(parts)-1]
if lexpr, ok := prevExpr.(*templateLiteralToken); ok {
lexpr.Val = strings.TrimRightFunc(lexpr.Val, unicode.IsSpace)
}
}
p.PushIncludeNewlines(false)
kw := p.Peek()
if kw.Type != TokenIdent {
if !p.recovery {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid template directive",
Detail: "A template directive keyword (\"if\", \"for\", etc) is expected at the beginning of a %{ sequence.",
Subject: &kw.Range,
Context: hcl.RangeBetween(next.Range, kw.Range).Ptr(),
})
}
p.recover(TokenTemplateSeqEnd)
p.PopIncludeNewlines()
continue Token
}
p.Read() // eat keyword token
switch {
case ifKeyword.TokenMatches(kw):
condExpr, exprDiags := p.ParseExpression()
diags = append(diags, exprDiags...)
parts = append(parts, &templateIfToken{
CondExpr: condExpr,
SrcRange: hcl.RangeBetween(next.Range, p.NextRange()),
})
case elseKeyword.TokenMatches(kw):
parts = append(parts, &templateEndCtrlToken{
Type: templateElse,
SrcRange: hcl.RangeBetween(next.Range, p.NextRange()),
})
case endifKeyword.TokenMatches(kw):
parts = append(parts, &templateEndCtrlToken{
Type: templateEndIf,
SrcRange: hcl.RangeBetween(next.Range, p.NextRange()),
})
case forKeyword.TokenMatches(kw):
var keyName, valName string
if p.Peek().Type != TokenIdent {
if !p.recovery {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid 'for' directive",
Detail: "For directive requires variable name after 'for'.",
Subject: p.Peek().Range.Ptr(),
})
}
p.recover(TokenTemplateSeqEnd)
p.PopIncludeNewlines()
continue Token
}
valName = string(p.Read().Bytes)
if p.Peek().Type == TokenComma {
// What we just read was actually the key, then.
keyName = valName
p.Read() // eat comma
if p.Peek().Type != TokenIdent {
if !p.recovery {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid 'for' directive",
Detail: "For directive requires value variable name after comma.",
Subject: p.Peek().Range.Ptr(),
})
}
p.recover(TokenTemplateSeqEnd)
p.PopIncludeNewlines()
continue Token
}
valName = string(p.Read().Bytes)
}
if !inKeyword.TokenMatches(p.Peek()) {
if !p.recovery {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid 'for' directive",
Detail: "For directive requires 'in' keyword after names.",
Subject: p.Peek().Range.Ptr(),
})
}
p.recover(TokenTemplateSeqEnd)
p.PopIncludeNewlines()
continue Token
}
p.Read() // eat 'in' keyword
collExpr, collDiags := p.ParseExpression()
diags = append(diags, collDiags...)
parts = append(parts, &templateForToken{
KeyVar: keyName,
ValVar: valName,
CollExpr: collExpr,
SrcRange: hcl.RangeBetween(next.Range, p.NextRange()),
})
case endforKeyword.TokenMatches(kw):
parts = append(parts, &templateEndCtrlToken{
Type: templateEndFor,
SrcRange: hcl.RangeBetween(next.Range, p.NextRange()),
})
default:
if !p.recovery {
suggestions := []string{"if", "for", "else", "endif", "endfor"}
given := string(kw.Bytes)
suggestion := nameSuggestion(given, suggestions)
if suggestion != "" {
suggestion = fmt.Sprintf(" Did you mean %q?", suggestion)
}
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid template control keyword",
Detail: fmt.Sprintf("%q is not a valid template control keyword.%s", given, suggestion),
Subject: &kw.Range,
Context: hcl.RangeBetween(next.Range, kw.Range).Ptr(),
})
}
p.recover(TokenTemplateSeqEnd)
p.PopIncludeNewlines()
continue Token
}
close := p.Peek()
if close.Type != TokenTemplateSeqEnd {
if !p.recovery {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: fmt.Sprintf("Extra characters in %s marker", kw.Bytes),
Detail: "Expected a closing brace to end the sequence, but found extra characters.",
Subject: &close.Range,
Context: hcl.RangeBetween(startRange, close.Range).Ptr(),
})
}
p.recover(TokenTemplateSeqEnd)
} else {
p.Read() // eat closing brace
// If the closer is ~} then we want to eat any leading
// whitespace on the next token, if it turns out to be a
// literal token.
if len(close.Bytes) == 2 && close.Bytes[0] == '~' {
ltrimNext = true
}
}
p.PopIncludeNewlines()
default:
if !p.recovery {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Unterminated template string",
Detail: "No closing marker was found for the string.",
Subject: &next.Range,
Context: hcl.RangeBetween(startRange, next.Range).Ptr(),
})
}
final := p.recover(end)
endRange = final.Range
break Token
}
}
if len(parts) == 0 {
// If a sequence has no content, we'll treat it as if it had an
// empty string in it because that's what the user probably means
// if they write "" in configuration.
parts = append(parts, &templateLiteralToken{
Val: "",
SrcRange: hcl.Range{
// Range is the zero-character span immediately after the
// opening quote.
Filename: startRange.Filename,
Start: startRange.End,
End: startRange.End,
},
})
}
// Always end with an end token, so the parser can produce diagnostics
// about unclosed items with proper position information.
parts = append(parts, &templateEndToken{
SrcRange: endRange,
})
ret := &templateParts{
Tokens: parts,
SrcRange: hcl.RangeBetween(startRange, endRange),
}
return ret, diags
}
// flushHeredocTemplateParts modifies in-place the line-leading literal strings
// to apply the flush heredoc processing rule: find the line with the smallest
// number of whitespace characters as prefix and then trim that number of
// characters from all of the lines.
//
// This rule is applied to static tokens rather than to the rendered result,
// so interpolating a string with leading whitespace cannot affect the chosen
// prefix length.
func flushHeredocTemplateParts(parts *templateParts) {
if len(parts.Tokens) == 0 {
// Nothing to do
return
}
const maxInt = int((^uint(0)) >> 1)
minSpaces := maxInt
newline := true
var adjust []*templateLiteralToken
for _, ttok := range parts.Tokens {
if newline {
newline = false
var spaces int
if lit, ok := ttok.(*templateLiteralToken); ok {
orig := lit.Val
trimmed := strings.TrimLeftFunc(orig, unicode.IsSpace)
// If a token is entirely spaces and ends with a newline
// then it's a "blank line" and thus not considered for
// space-prefix-counting purposes.
if len(trimmed) == 0 && strings.HasSuffix(orig, "\n") {
spaces = maxInt
} else {
spaceBytes := len(lit.Val) - len(trimmed)
spaces, _ = textseg.TokenCount([]byte(orig[:spaceBytes]), textseg.ScanGraphemeClusters)
adjust = append(adjust, lit)
}
} else if _, ok := ttok.(*templateEndToken); ok {
break // don't process the end token since it never has spaces before it
}
if spaces < minSpaces {
minSpaces = spaces
}
}
if lit, ok := ttok.(*templateLiteralToken); ok {
if strings.HasSuffix(lit.Val, "\n") {
newline = true // The following token, if any, begins a new line
}
}
}
for _, lit := range adjust {
// Since we want to count space _characters_ rather than space _bytes_,
// we can't just do a straightforward slice operation here and instead
// need to hunt for the split point with a scanner.
valBytes := []byte(lit.Val)
spaceByteCount := 0
for i := 0; i < minSpaces; i++ {
adv, _, _ := textseg.ScanGraphemeClusters(valBytes, true)
spaceByteCount += adv
valBytes = valBytes[adv:]
}
lit.Val = lit.Val[spaceByteCount:]
lit.SrcRange.Start.Column += minSpaces
lit.SrcRange.Start.Byte += spaceByteCount
}
}
type templateParts struct {
Tokens []templateToken
SrcRange hcl.Range
}
// templateToken is a higher-level token that represents a single atom within
// the template language. Our template parsing first raises the raw token
// stream to a sequence of templateToken, and then transforms the result into
// an expression tree.
type templateToken interface {
templateToken() templateToken
}
type templateLiteralToken struct {
Val string
SrcRange hcl.Range
isTemplateToken
}
type templateInterpToken struct {
Expr Expression
SrcRange hcl.Range
isTemplateToken
}
type templateIfToken struct {
CondExpr Expression
SrcRange hcl.Range
isTemplateToken
}
type templateForToken struct {
KeyVar string // empty if ignoring key
ValVar string
CollExpr Expression
SrcRange hcl.Range
isTemplateToken
}
type templateEndCtrlType int
const (
templateEndIf templateEndCtrlType = iota
templateElse
templateEndFor
)
type templateEndCtrlToken struct {
Type templateEndCtrlType
SrcRange hcl.Range
isTemplateToken
}
func (t *templateEndCtrlToken) Name() string {
switch t.Type {
case templateEndIf:
return "endif"
case templateElse:
return "else"
case templateEndFor:
return "endfor"
default:
// should never happen
panic("invalid templateEndCtrlType")
}
}
type templateEndToken struct {
SrcRange hcl.Range
isTemplateToken
}
type isTemplateToken [0]int
func (t isTemplateToken) templateToken() templateToken {
return t
}