initial commit

1 files changed, 158 insertions, 0 deletions

diff --git a/nimrec.nim b/nimrec.nim
new file mode 100644
index 0000000..034bbfc
--- /dev/null
+++ b/nimrec.nim
@@ -0,0 +1,158 @@
+import streams
+import strutils
+import tables
+
+type
+    Field* = ref object
+        label*: string
+        value*: string
+
+    Record* = ref object
+        fields: OrderedTableRef[string, seq[string]]
+
+    ParseState {.pure.} = enum
+        Initial
+        Comment
+        Label
+        Value
+        ValueSkipSpace
+        FieldReady
+
+    RecParser* = ref object
+        state: ParseState
+        field: Field
+        record: Record
+
+    RecParseError* = object of Exception
+
+const
+    LabelFirstChar = {'a'..'z', 'A'..'Z', '%'}
+
+    LabelChar = {'a'..'z', 'A'..'Z', '0'..'9', '_'}
+
+    EofMarker = '\0'
+
+proc newRecParser*(): RecParser =
+    new(result)
+    result.state = ParseState.Initial
+
+proc newField(): Field =
+    new(result)
+    result.label = ""
+    result.value = ""
+
+proc newField(label, value: string): Field =
+    new(result)
+    result.label = label
+    result.value = value
+
+proc newRecord(): Record =
+    new(result)
+    result.fields = newOrderedTable[string, seq[string]]()
+
+proc feed*(parser: RecParser, ch: char, record: var Record): bool =
+    while true:
+        case parser.state
+        of ParseState.Initial:
+            case ch
+            of '#':
+                parser.state = ParseState.Comment
+            of '\l', EofMarker:
+                if parser.record != nil:
+                    result = true
+                    record = parser.record
+                    parser.record = nil
+            of LabelFirstChar:
+                parser.state = ParseState.Label
+                parser.field = newField()
+                parser.field.label &= ch
+            else:
+                raise newException(RecParseError, "parse error: expected a comment, a label or an empty line")
+        of ParseState.Comment:
+            case ch
+            of '\l':
+                parser.state = ParseState.Initial
+            else: discard
+        of ParseState.Label:
+            case ch
+            of ':':
+                parser.state = ParseState.ValueSkipSpace
+            of LabelChar:
+                parser.field.label &= ch
+            else:
+                raise newException(RecParseError,
+                    "parse error: invalid label char: " & ch)
+        of ParseState.Value:
+            case ch
+            of '\l':
+                let valueLen = len(parser.field.value)
+                if valueLen > 0 and parser.field.value[valueLen-1] == '\\':
+                    setLen(parser.field.value, valueLen - 1)
+                else:
+                    parser.state = ParseState.FieldReady
+            of EofMarker:
+                raise newException(RecParseError,
+                    "parse error: value must be terminated by a newline")
+            else:
+                parser.field.value &= ch
+        of ParseState.ValueSkipSpace:
+            case ch
+            of (WhiteSpace - NewLines):
+                discard
+            else:
+                parser.field.value &= ch
+            parser.state = ParseState.Value
+        of ParseState.FieldReady:
+            case ch
+            of '+':
+                parser.state = ParseState.ValueSkipSpace
+                parser.field.value &= '\l'
+            else:
+                if parser.record == nil:
+                    parser.record = newRecord()
+                if hasKey(parser.record.fields, parser.field.label):
+                    add(parser.record.fields[parser.field.label], parser.field.value)
+                else:
+                    add(parser.record.fields, parser.field.label,
+                        @[parser.field.value])
+                parser.field = nil
+                parser.state = ParseState.Initial
+                continue
+
+        break
+
+proc `[]`*(record: Record, label: string): string =
+    result = record.fields[label][0]
+
+proc len*(record: Record): int =
+    result = len(record.fields)
+
+iterator records*(stream: Stream): Record =
+    let parser = newRecParser()
+    var record: Record
+
+    while true:
+        var ch = readChar(stream)
+
+        if feed(parser, ch, record):
+            yield record
+
+        if ch == EofMarker:
+            break
+
+iterator pairs*(record: Record): (string, string) =
+    for label, values in record.fields:
+        for value in values:
+            yield (label, value)
+
+iterator items*(record: Record): Field =
+    for label, value in record:
+        yield newField(label, value)
+
+proc hasField*(record: Record, label: string): bool =
+    for field in record:
+        if field.label == label:
+            return true
+
+proc contains*(record: Record, label: string): bool =
+    result = hasField(record, label)