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zeekay
a4debdba80
C had no front end for the schema language at all. The compiler directory holds a code generator plugin, which is handed a request by another tool and never sees schema text, so a .zap file could not be read here in either form -- indentation or braces. zapgen reads it. Whitespace-significant source is rewritten into the brace form BEFORE the parser, exactly as the Go reference does it: a near identity that only adds the two tokens the brace grammar requires where the indented form leaves them out. A file already in braces comes back byte for byte, so one grammar reads both styles and neither is a dialect of the other. The identifier grammar is not restated. Its Unicode ranges are taken from Go's own tables by gen/table, so a name this parser accepts is a name the Go parser accepts, and a Go release that moves Unicode moves both. The generated header gives each struct a view over the message bytes and one reader per field at a fixed offset. Reading is in place and total: a field past the end reads zero, a pointer into the head or out of the message reads null. zap_view.h is the one place that says so. Checked against the Go front end on every .zap in the estate plus 55 adversarial cases and 15000 random ones: the brace form each writes is byte-identical, the layout each reads is field-for-field the same, and they accept and refuse the same files for the same stated reason. A message built by the Go runtime reads back through these bindings with every field equal.
42 lines
1.0 KiB
Plaintext
42 lines
1.0 KiB
Plaintext
# The schema this generator is checked against, written the way schemas
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# are written: no braces, no offsets. Indentation opens a block, and each
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# field takes the next free byte after the one before it.
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#
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# It names every type the dialect has, so the header generated from it
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# exercises every reader.
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package echo
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type id32 = bytes_fixed[32]
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# What one peer says.
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struct Ping
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# The sequence number the reply must carry back.
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Seq u64
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Sender id32
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Note text
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Payload bytes
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Hops u16
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Live bool
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Drift f64
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Trail list<Ping>
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Origin Site
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# Where a message came from.
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struct Site
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Host u32
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Port u16
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# What the other peer says back.
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struct Pong
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Seq u64
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Delay f32
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# Echo answers what it is told, and says how long it took.
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interface Echo
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# Say something and wait to hear it back.
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ping(req: Ping) returns (resp: Pong)
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# Say something and do not wait.
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notify(req: Ping)
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# Ask whether the other side is there at all.
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health() returns (resp: Pong)
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