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parser.go
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parser.go
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package got
import (
"strings"
)
type parser struct {
lexer *lexer
}
func parse(l *lexer) tokenItem {
p := parser{lexer:l}
topItem := tokenItem{typ: itemGo}
var endItem tokenItem
topItem.childItems, endItem = p.parseRun()
// if we have an error that has no call stack, extract all the errors from the channel and build a call stack from them
if endItem.typ == itemError {
if len(endItem.callStack) <= 1 {
for item := range p.lexer.items {
if item.typ == itemError {
endItem.callStack = append(endItem.callStack, item.callStack[0])
}
}
}
return endItem
}
return topItem
}
func (p *parser) parseRun() (subItems []tokenItem, endItem tokenItem) {
for item := range p.lexer.items {
switch item.typ {
case itemEOF:
endItem = item
return
case itemError:
endItem = item
return
case itemRun:
subItems = append(subItems, item)
case itemStrictBlock:
subItems = append(subItems, item)
case itemEnd:
endItem = item
return
case itemEndBlock:
endItem = item
return
case itemText:fallthrough
case itemGo:
item.childItems, endItem = p.parseRun()
if endItem.typ == itemEOF {
endItem.typ = itemError
endItem.val = "unexpected end of file"
return
}
if endItem.typ != itemEnd {
return
}
subItems = append(subItems, item)
case itemString: fallthrough
case itemBool: fallthrough
case itemInt: fallthrough
case itemUInt: fallthrough
case itemFloat: fallthrough
case itemInterface: fallthrough
case itemBytes: fallthrough
case itemGoErr:
item2 := p.parseValue(item)
if item2.typ == itemError {
endItem = item2
return
}
subItems = append(subItems, item2)
case itemIf:
ifItems := p.parseIf(item)
if len(ifItems) > 0 {
if ifItems[0].typ == itemError {
endItem = ifItems[0]
return
}
// push the if items down to the childItems of overriding if item
ifItem := tokenItem{typ: itemIf, childItems: ifItems}
subItems = append(subItems, ifItem)
}
case itemJoin:
item2 := p.parseJoin(item)
if item2.typ == itemError {
endItem = item2
return
}
subItems = append(subItems, item2)
case itemFor:
item2 := p.parseFor(item)
if item2.typ == itemError {
endItem = item2
return
}
subItems = append(subItems, item2)
default:
panic("unexpected token") // this is a programming bug, not a template error
}
}
endItem.typ = itemEOF
return
}
func (p *parser) parseValue(item tokenItem) tokenItem {
runItem := <- p.lexer.items
switch runItem.typ {
case itemRun:
item.val = strings.TrimSpace(runItem.val)
if item.val == "" {
item.typ = itemError
item.val = "missing value"
return item
}
case itemEnd:
item.typ = itemError
item.val = "missing value"
return item
case itemEOF:
item.typ = itemError
item.val = "unexpected end of file"
return item
case itemError:
return runItem
default:
runItem.typ = itemError
runItem.val = "unexpected text inside a value block"
return runItem
}
endItem := <- p.lexer.items
switch endItem.typ {
case itemEnd:
return item // correctly terminated a value
case itemEOF:
endItem.typ = itemError
endItem.val = "unexpected end of file"
return endItem
case itemError:
return endItem
default:
endItem.typ = itemError
endItem.val = "unexpected text inside a value block"
return endItem
}
}
func (p *parser) parseIf(item tokenItem) (items []tokenItem) {
if item.typ != itemElse {
conditionItem := <-p.lexer.items
switch conditionItem.typ {
case itemRun:
item.val = strings.TrimSpace(conditionItem.val)
case itemEnd:
conditionItem.typ = itemError
conditionItem.val = "missing condition in if statement"
return []tokenItem{conditionItem}
case itemEOF:
conditionItem.typ = itemError
conditionItem.val = "unexpected end of file"
return []tokenItem{conditionItem}
case itemError:
return []tokenItem{conditionItem}
default:
conditionItem.typ = itemError
conditionItem.val = "unexpected text inside a value definition"
return []tokenItem{conditionItem}
}
endItem := <-p.lexer.items
switch endItem.typ {
case itemEnd:
// correctly terminated a value, so keep going
case itemEOF:
endItem.typ = itemError
endItem.val = "unexpected end of file"
return []tokenItem{endItem}
case itemError:
return []tokenItem{endItem}
default:
endItem.typ = itemError
endItem.val = "unexpected text inside an if statement"
return []tokenItem{endItem}
}
}
var endItem tokenItem
// get the items inside the if statement
item.childItems, endItem = p.parseRun()
switch endItem.typ {
case itemEndBlock:
// correctly terminated a value, so keep going
case itemEOF:
endItem.typ = itemError
endItem.val = "unexpected end of file"
return []tokenItem{endItem}
case itemError:
return []tokenItem{endItem}
default:
endItem.typ = itemError
endItem.val = "unexpected end of an if statement"
return []tokenItem{endItem}
}
switch endItem.val {
case "if":
// terminated the if statement
return []tokenItem{item}
case "else":
if item.typ == itemElse {
// cannot place an else after an else
endItem.typ = itemError
endItem.val = "cannot put an else after another else"
return []tokenItem{endItem}
}
elseItem := endItem
elseItem.typ = itemElse
items3 := p.parseIf(elseItem)
if len(items3) > 0 {
switch items3[0].typ {
case itemError:
return []tokenItem{items3[0]}
case itemEOF:
elseItem.typ = itemError
elseItem.val = "unexpected end of file"
return []tokenItem{elseItem}
}
}
items = append(items, item)
items = append(items, items3...)
return
case "elseif":
if item.typ == itemElse {
// cannot place an else after an else
item.typ = itemError
item.val = "cannot put an elseif after an else"
return []tokenItem{item}
}
elseIfItem := item
elseIfItem.typ = itemElseIf
items3 := p.parseIf(elseIfItem)
if len(items3) > 0 {
switch items3[0].typ {
case itemError:
return []tokenItem{items3[0]}
case itemEOF:
elseIfItem.typ = itemError
elseIfItem.val = "unexpected end of file"
return []tokenItem{elseIfItem}
}
}
items = append(items, item)
items = append(items, items3...)
return
default:
item.typ = itemError
item.val = "unexpected end block item"
return []tokenItem{item}
}
}
func (p *parser) parseFor(item tokenItem) tokenItem {
conditionItem := <-p.lexer.items
switch conditionItem.typ {
case itemRun:
item.val = strings.TrimSpace(conditionItem.val)
case itemEnd:
conditionItem.typ = itemError
conditionItem.val = "missing condition in for statement"
return conditionItem
case itemEOF:
conditionItem.typ = itemError
conditionItem.val = "unexpected end of file"
return conditionItem
case itemError:
return conditionItem
default:
conditionItem.typ = itemError
conditionItem.val = "unexpected text inside a value definition"
return conditionItem
}
endItem := <-p.lexer.items
switch endItem.typ {
case itemEnd:
// correctly terminated a value, so keep going
case itemEOF:
endItem.typ = itemError
endItem.val = "unexpected end of file"
return endItem
case itemError:
return endItem
default:
endItem.typ = itemError
endItem.val = "unexpected text inside an if statement"
return endItem
}
// get the items inside the for statement
item.childItems, endItem = p.parseRun()
switch endItem.typ {
case itemEndBlock:
// correctly terminated a value, so keep going
if endItem.val != "for" {
endItem.typ = itemError
endItem.val = "unexpected end block of for, got: " + endItem.val
return endItem
}
case itemEOF:
endItem.typ = itemError
endItem.val = "unexpected end of file"
return endItem
case itemError:
return endItem
default:
endItem.typ = itemError
endItem.val = "unexpected end of a for statement"
return endItem
}
return item
}
func (p *parser) parseJoin(item tokenItem) tokenItem {
sliceItem := <-p.lexer.items
connectorItem := <-p.lexer.items
if sliceItem.typ != itemParam || connectorItem.typ != itemParam {
item.typ = itemError
item.val = "expected parameter of join statement"
return item
}
item.params = make(map[string]tokenItem)
item.params["slice"] = sliceItem
item.params["joinString"] = connectorItem
endItem := <-p.lexer.items
if endItem.typ != itemEnd {
endItem.typ = itemError
endItem.val = "expected end of join statement"
return endItem
}
item.childItems, endItem = p.parseRun()
if endItem.typ != itemEndBlock || endItem.val != "join"{
endItem.typ = itemError
endItem.val = "expected ending join tag"
return endItem
}
return item
}