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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.
28 lines
921 B
C
28 lines
921 B
C
/* SPDX-License-Identifier: BSD-3-Clause-Eco */
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/*
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* emit.h - the schema, said in C.
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*
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* One header per schema. Every struct becomes a view over the message
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* bytes and one reader per field that takes its value from a fixed offset,
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* so a read is an offset and a load, never a parse. Every interface becomes
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* its method ordinals, which declaration order fixes for good.
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*/
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#ifndef ZAPGEN_EMIT_H
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#define ZAPGEN_EMIT_H
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#include "schema.h"
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#include <stdio.h>
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/* emit writes the C header for f to out. Returns 0, or -1 with the reason
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* in err when the schema declares a layout that cannot be read (a field
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* overlapping another, a struct with no fields, a method naming a struct
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* the file does not declare). */
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int emit(const struct zap_file *f, FILE *out, char err[512]);
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/* check runs the same reading of the schema without writing anything. */
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int check(const struct zap_file *f, char err[512]);
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#endif
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